I spent a nice day , especially as I spoke to a friend over Skype.

You could say “I spent a nice day speaking to a friend over Skype” or “I spent some time speaking to a friend over Skype”

She corrected me on a bunch of words.

We also changed our opinion abouton differencet topics.

Before sleeping, I'm going to read my book and pray.

You would more commonly say “before bed” or “before going to sleep”

I spenthad a nice day , especially as I spoke to a friend over Skype.

to spend a day = to dedicate an entire day to something, like "i spent a day shopping"
you just wanted to describe what kind of day you experienced, or *had*

We sopoke in French, then in Spanish, and finally in English.

spoke i'm sure was just a typo lol

in english, we put a comma before the last item in a series before the word "and" - it's called an oxford comma. it's to emphasize that the two items, separated by "and", are still 2 separate items and shouldn't be thought of as two things acting together as 1 item in a list. there is technically some controvery over whether or not it is required or just optional, but omitting an oxford comma can sometimes cause for interesting misunderstandings. the most common examples are related to when we separate names with commas (i can't think of what this is grammatically called in english - interjectory clauses, i guess?):

i love my parents, my dog, and my cat = you love 3 things and those things are 1. your parents 2. your dog 3. your cat
i love my parents, my dog and my cat = you love your parents, and your parents are your dog & your cat

we invited the strippers, JFK, and Stalin = you invited 3 people, and those 3 people were 1. some strippers 2. JFK 3. Stalin
we invited the strippers, JFK and Stalin = you invited strippers, and those strippers were JFK and Stalin. lmao

She corrected me a bunch of words.

or: she corrected a bunch of words for me

We also changed our opinions about differencet topics.

this sentence means that, through your conversation, your opinion about something was different by the end of the conversation.

if your opinion on something stayed the same throughout the conversation, but you just shared your opinions with each other, you have to say:
We also exchanged our opinion about different topics
although this sounds unnatural, and a better phrasing would be:
We also shared our opinions about different topics

Before sleeping, I'm going to read my book and pray.

"Before going to sleep" sounds more natural, but yours is not grammatically incorrect

I spenthad a nice day , especially asbecause I spoke to a friend over Skype.

We sopoke in French, then in Spanish and finally in English.

Very nice!

She corrected me a bunch of wordtimes.

We also exchanged our opinions about differencet topics.