Complex sentence: Right next door is Mitch's best friend, Russell, a stand-up comedian and often Mitch's voice of reason, and Russell's new wife Angie, who always keeps him in check.
Split into simpler sentences: Right next door is Mitch's best friend, Russell, a stand-up comedian and often times Mitch's voice of reason. Then there's Russell's new wife Angie, who always keeps him in check.