Perimeter means you need to add all of the sides together whereas area means length times width.
Once you know that, you have to decide the shape of the parking lot. Most parking lots are rectangles, and we know that's the case here because the length and width are different (they'd be the same if it was a square).
So, there are two sides considered length and two sides considered width. That means the perimeter is found by adding 300 + 300 + 100 + 100.
The unit will be feet.
To find the area, multiply length by width 300 x 100.
The unit for area will be feet squared or feet to the power of two (this is ALWAYS the case for area ie the unit will always be squared)
I'd love to help you with more problems like this one! Just send me a message so we can schedule a lesson :)