Hey there!
* hold one's liquor = to be able to drink alcohol in quantity without ill effects. It is an expression used to indicate when a person might be able to drink alcohol without displaying any side effects such as puking, slurring speech, emotional changes, etc.
E.g.: ''I asked him to leave because he can not hold his liquor.''
E.g.: ''Old Jon can sure hold his liquor - and a lot of it, too.''
Hope that helps!