Okay kiddo, a church is a place where people go to worship God and learn about their religion. The Assyrian Pentecostal Church is a specific church for people who are Assyrian (which is a type of ethnic group from the Middle East) and also practice the Pentecostal religion.
Pentecostal is a type of Christianity where people believe in the Holy Spirit. Some special things happen when people can feel the Holy Spirit in their hearts, like speaking in different languages or having a really good feeling inside.
In the Assyrian Pentecostal Church, people sing songs, pray, and listen to a priest talk about the Bible and how to be a good person. It's a place where people can come together to grow in their faith and support each other.