First of all welcome to the forum! Second: congratulations for considering adoption!
The female is most likely pregnant if she has been kept with an unaltered male. Has the Humane Society separated them yet? If not call and make sure they are separated right away.
Since I don't know you it's hard for me to tell you whether or not you'd be getting in over your head. So instead I'm going to tell you what would be involved in taking these two if the female is pregnant.
First you would need to build a big enough cage. That is easy enough and the home page here explains how to do it. It is cheaper than buying pet store cages that do not give enough room.
Second you would have to learn how to properly care for guinea pigs. This thread is a good place to start:
https://www.guineapigcages.com/forum/showthread.php?t=17032 They need to be free fed hay, quality pellets and fresh veggies and water every day.
Third you will need to have a quality cavy savvy vet on hand if something goes wrong during the birth. As much as I hope it's not the case, birthing complications are a possibility.
Fourth you will need to sex the pups. This page will help:
https://cavyspirit.com/sexing.htm It is very important that male pups are separated at three weeks of age. After this they will get their mom or sisters pregnant.
Fifth you will need to either care for or find good home for the pups. She could have a liter anywhere between 1 and 7 (though I think between 2 and 5 is more common).
This is a good site to learn information on the reproduction of guinea pigs:
https://www.guinealynx.info/reproduction.html
Read through everything you can on these sites:
https://www.guinealynx.info/index.html
https://cavyspirit.com/
For neutering information read this page:
https://cavyspirit.com/neutering.htm
For help finding a cavy savvy vet read this page:
https://www.guinealynx.info/vet.html
If you have any questions feel free to ask.