[noun (place)] + に + [noun (animate)] + が + いる
[noun (person)] + には + [noun (animate)] + が + いる
Note: いる is a る-verb (v1); conjugates as いる / いた / いない / いなかった / います (polite)
The verb いる is used to indicate the existence or presence of animate beings such as people, animals, or other living creatures. On the other hand, ある is used for inanimate objects
The location of the being is marked with に, and the living subject is marked with が.
いる is a る-verb.
It conjugates regularly, just like other る-verbs.