I have picked up ukulele and have realized that the softer strings have helped me get used to the harder guitar strings. I was wondering if they made softer strings for a normal sized acoustic guitar that won't damage the guitar or ruin the sound. I ask this because my husband is trying to learn and I thought that maybe if he had softer strings it would help in his learning. .
Well, guitar necks are designed to bear a certain amount of tension and strings which don't provide that tension will likely cause the instrument to become warped.
Having said that, classical guitars (which are a different style of guitar designed for different strings) use strings similar to the ones on your ukelele, although the bass strings are wound, they are also softer and have less tension. But switching from steel string guitar to classical guitar on the basis of making the strings a bit more comfortable to play may not be a good plan because the result will affect alot of other things. The neck will by wider, the tone will sound different, a pick is not normally used, and the guitar's sound lends itself more to certain kinds of music than others.
There are also "Silk & Steel" strings which some people think feel a bit lighter on the hands.
Probably the most reasonable thing to do is just use the lightest-gauge steel strings for acoustic guitar that he can find. That would make it easier to play without affecting anything else too much. But they won't have the soft feeling of ukelele strings.
There have been several similar questions here. I recommend lighter gauge strings, which will not be so tight. Ones for electric guitar will do, but you need to establish what gauge is on already. Them drop by a couple of sizes - if originals are 011s, go to 009s.There may also be an issue with the action of the guitar, causing the strings to need pressing too far onto the fingerboard in the first place.Nylon type strings will not be a good answer.