Questions about example sentences with, and the definition and usage of "Genuflect"

A: Mock, in this case, means "fake" or "pretend". To mock-(something) is to pretend like you are doing that thing. This person is pretending to shriek (scream). They are faking that they are surprised/angry/scared/amazed/etc. and probably being sarcastic.

Genuflect = Get on your knees. When someone goes to church, they genuflect to pray. Or someone might genuflect in front of a king to show respect.

li'l = This is a contraction of "little". It is mostly only used in spoken English and not often in written English.

Genuflect a li'l = Genuflect a little (bit).

If they don't literally mean to get on one's knees, they probably mean "show some respect" or "act more humble". (In your case I'm not sure. I think she means she is impressed.)