Uranus is an “ice” giant, which is a type of a gas giant. It’s outer layers are mostly hydrogen and helium gas — same as Jupiter, Saturn, Neptune and even the Sun. Uranus has lots of ice mixed in to these layers though.
Some of the ice is water ice like what we’re used to. But there’s also ammonia and methane ice — you can find them on Earth as gases, but Uranus is so cold (-224 degrees) that they turn to ice.
The inner bits of Uranus is made mostly from ice as well with some rock mixed in, although since we’ve never been to Uranus and it has such a thick atmosphere, it’s really hard to tell from Earth!