English Learning : What does mean by "Formality.......

Dear Writing Experts,

My Eglish lecturer always mentions two technical terms in learning writing, do you know what does it mean by "Formality" and "Collocation" in learning writing? I have done a lot of excercises about them but I am still feeling confused for the chinese interpretation.

(1) Formality- 是否指句子的正規性

(2) Collocation-是否指句子的舖排嗎?

Thanks for you help.

Merry Christmas!