I have seen her

the tense is determined by the verb form: seen.
seen is the past participle tense of the verb, see.
MY q is: why we still say: present perfect tense.
What does present mean in the phrase
AFAIK, tense does not include the auxiliary, then why still we say perfect here.
Why do we not say for the simple past tense that it is perfect tense.
What makes a tense perfect?

Please help me sort it out.