Can someone tell me why when I put my pump on I get a white foam from the return??

More info is needed. Is it brand new? Used? Could be soap residue if the previous owner had a suds party.. please provide a little more information for us to be able to answer your question

Go to the store and buy a defoamer and put in it.

Hi,
Too much "cleaner" in the water.
I had an above ground swimming pool, which my family and I used for about 20 yrs, had a lot of fun with it.
Besides chlorine and keeping the pH levels correct, there was a "cleaner" that could be added. It was supposed to coagulate small material, into larger particles that could be caught by the filter. I added too much one time, and got foam all over the top. Looked like I had added Dawn detergent to the water!
Check if you are adding any "coagulation" liquid to the pool or spa. Stop using it, if you are. I do wish you the best, and good luck.