Add data in cell A to the front of data in cellB

I imagine this is really simple for one of you experts but a quick search yielded no results. I am trying to import a csv file containing contact information

The file I am importing from lists telephone information in 2 columns. Column a has the area code and column b has the other 7 digits of the phone number. The correct format is all 10 digits in a sigle column. It seems to me the bezst way to accomplish this would be to somehow merge the data in these cells but it has been a while since I used excel and my old brain seems to have forgotten some of its tricks.

Thanks in advance to anyone who is able to help me out here. It is greatly appreciated.

Thanks,

Exactly perfect 100% what I wanted thank you sir

I have added to your rep as well.