does for singular subject. and do for pupolar. verbs to do ( does, do and did) can be main verb and can be auxiliary verb. if we use these verb as main verbs, it take meaning as "act" e.g I do my homeworks if we use them as an auxiliary it doesn't have meaning or to assure the verb ( such if we don't use it the meaning of the sentence will stay correct) example: "I do appreciate" it has the same meaning as " I appreciate" but the first one is more intensive

"Do" is a verb which you use for almost every person. e.g. Do you play soccer?, Do we play soccer?, Do I play soccer?, Do they play soccer? The exception is he/she/it, that's the case when you always have to use "does". e.g. Does she play soccer?, Does he play soccer?, Does it rain? (the same example does not make much sense) Of course this is just the case in the simple present, so not in the past or future.