We have a little money to go on holidays.

“Little” by itself like that is typically used more as an adjective. Something like “a little” or “too little” would be a quantitative amount.

I have a/too little time to finish my homeworks befor moe Monday.

“I don’t have enough time…” sounds more natural though.
Homework stays as homework in its plural form.
Days of the week are capitalised.

This bed is a fewbit too big for the four of us.

“A few” would be used if you were talking about a plural thing in this case.
For example “There are a few too many beds for the four of us.”
“Four of us” wasn’t entirely incorrect, but I tend to add “the” in front in cases like this.

I think she speaks a little clearly.

All hadEveryone undrerstood what she meant.

The first sentence may have technically been right but using “everyone” is more common.

You are going a little fast.

I studyied a little and I failed the test.

Failed = past tense, so study —> studied

If you wanted to keep study in the present tense, then you would need to add a time word like always. For example: “I always study and I still failed the test.”
I removed the “a little” because it doesn’t sound the best in this case.

He earns a little money to support his familiy.

We have little money to go on holidays.vacation

according to your sentence, i think it should be for traveling, so i change its word.

I have littlemited time to finishcomplete my homeworks befor moe Monday.

by the way, Just remember the plural form of homework is homework, you don't need to add s.
Although most plural form add s, but be aware that are some exception that does not add s.
Also for the name of days, We should capitalize all the first letter, For example, Monday, Tuesday, Wednesday,....

This bed is a fewbit too big for four of us.

few big, maybe you mean a big too big?, but by the context it make more sense if you say it is too small.

I think she speaks a littlquite clear.

All hadEveryone undrerstood what she meant.

You are going a little fast.

I studyied a little and I failed the test.

I was too tired to go clubbing.

I was too exhausted to go clubbing.
or maybe write this to make it sound more natural?

I have little time to finish my homeworks befor moe Monday.

All days of the week are pluralized and the plural of homework is homework just as the plural of work is work.

This bed is a few bignot big enough for four of us.

When speaking about specifications in relation to fitting the needs of individuals, the word "enough" is used to indicate that it is suitable. For example: "The lamp is not bright enough" - If you wanted a brighter lamp.

I think she speaks a little clear.clearly enough. (?)

Not completely sure about the intention of this sentence but if it was to indicate the clarity of the person's voice is suitable to you, then this is what would be said.

All had undreEveryone had understood what she meant. OR All understood what she meant.

Just depends on what your intention with the sentence was. If you wanted to say that she understood by everyone previously then use the first one. For the second one, it is just a more poetic version of the first one which gives the sentence an elevated tone; therefore, it sounds more important.

You are going little too fast.

What was said before can also be used; it is just more colloquial which might be what you intended.

I study a little and I failed the test.

I think you don't sleep enough OR I think you rarely sleep OR I think you hardly sleep OR I think you should sleep a little.

Not sure what the intended meaning of the sentence was, but note the following:

If you were concerned that the person does not get enough sleep: Use the 1st.
If you think the person is frequently sleep deprived and just wanted to note the fact: Use 2nd and 3rd.
If you wanted the person to have a few minutes/hours of rest: Use the last one.

He earns a little money to support his familiy. OR He earns too little money to support his family

Just depends on what your intention was.

5-7-2nd27/05 or 05/27

We have littledon't have enough money to go on holidays.

Or, "We have too little money to go on holidays" but this is less common

I have little time to finish my homeworks befor moe Monday.

This bed is a fewlittle big for four of us.

I think she speaks a littlquite clearly.

You are going a little fast.

I studyied a little and I failed the test.

I think you sleep aget too little sleep.

Or, "I think you don't get enough sleep."

He earns a little money to support his familiy.