Yes, the base form of the verb is have. The past tense is had. The past participle is had. The present participle is having.
The verb have can be used in a variety of ways, including:
As a main verb (I have a cat)
An auxiliary verb (I am having lunch)
A modal verb (I might have left my phone at home)
It can also be used to indicate possession (Peter has a lot of money).