Gladys D. Asked "What are those buttons called at the bottom of all my [Android] screens?"

Great question Gladys!  There are three and they used to be physical buttons but now are just always part of the touchscreen.  We'll go from left to right. Here we go!

1. The triangle or arrow is called the "Back" button.  In older models this was a arrow that looped.

2. The middle button is usually a circle and is called the "Home" button.  In older models it looks like a house.

3. The button on the right is usually a square and is called the "Overview" button.  In older models it looks like multiple rectangles.

Thanks Gladys!
Sincerely,
The Senior Dummy