Solid
Steady, Firm
い adjective
You know that 堅い is "solid" or "tough." When your hand is solid and tough, it's solid and steady. If your hand is shaky, it's the opposite, or something.
The reading is the two words 手 and 堅い combined together. Watch out for the rendaku.
中々手堅い仕事みたいだから、葬儀屋になるための勉強をしようかなって思ってるんだよね。
I’m thinking of learning how to become an undertaker because it looks like a pretty secure job.