Rev.

[POPS]

I need feet on square feet, on a 5 acres piece of land

[POPS]

I need feet not square feet, on a 5 acres piece of land

[Robert Fogt]

There are 43560 square feet in an acre.

5 acres * 43560 square foot/acre = 217800 square foot

You can also use the Area conversion page here:
http://www.onlineconversion.com/area.htm