Breakfast habits can vary by countries.

Turkish breakfast is made up of multiple items such as jam, cheese, olives, green leaveas, tomatoes, cucumbrers etc, h. However, European breakfast habits is to eat very small breakfasts.

Jam and cheese are uncountable. the rest would usually be all plural (or they could be all singular). I am not sure what "green leaves" means though...perhaps "salad greens"? lettuce and such? and I would break this into two sentences. I modified the word order in the second sentence to sound more "native."

It is comprised of coffee/tea and a croissant.

a croissant OR croissants.

In this regard, a Turkish person can skip lunch, if he/she has brekakfast at 10.30 but skipping lunch may be difficult for an European.

a Turk or a Turkish person. and I know it seems that it should be "an European" but it's "a European" - I don't know why. sorry!

Having breakfast is a ceremony in Turkey and there is a saying "Breakfast must have something to do with happiness".

I like that saying!

Because aAn accountant sits the whole day and he does not consume his energiesy and calories while a construction worker uses up his energy by working physically.

to use "because" it should be merged with the prior sentence. I'd just remove it; it's not necessary.

Therefore, we cannot say anybody can skip the breakfast.

For me, I have the breakfast at 11.00 and do not feel like eating other meals.

This habit makes me feel better and light.

This isn't quite how a native would say it, although it is grammatically correct. maybe "better and lighter" would work better