"To jídlo je pro Matěje."

[maria1895]

I said "This food is for Matej." Does it have to be "the food"?

[endless_sleeper]

Toto = 'this'

[Tommyxr]

Why is Matěj accusative with the verb být?

Is it because of "pro"? Like would "Ten muž je Matěj" but there it's Matěje because it is PRO Matěj?

[VladaFu]

Yes, pro takes accusative. The same is German für, also takes accusative.

[Tommyxr]

Děkuji!

Is it the same thing with possessives pronouns? Would I say to je můj přitele?

[BoneheadBass]

In your sentence, you would use "přitel," because the verb is "je" and you need the nominative case. But you are right that "přítele" would be the accusative form. So, if you wanted to say, "I HAVE a friend," for example, you could say, "Já mám přítele."