What deos assemble mean?

Assemble means come together or put together.

You assemble car parts. You assemble a model aeroplane, you assemble a child's swing set.

Assembly means coming together. Churches have an assembly. School functions have an assembly where all the children gather at a common point.

There are Assembly Stations, such as on the deck of a ship. In an emergency passengers would be instructed to go to their assembly or muster points.

The americans have a church group called the assembly of God - it's a group of churches who come together for prayer.