Tubeless tires are tires that do not use an inner tube. The tire fits snugly on the bike rim, and it can have a liquid sealant that seals small punctures automatically.
They are a favorite of mountain and gravel riders. They reduce the likelihood of pinch flats, enable you to ride on less air pressure for improved traction, and are more comfortable on harsher surfaces. They require matching rims and valves and may be more troublesome to install than standard tires. You must add sealant periodically and although tubeless tires will seal small holes on their own, larger ones might require a plug or tube assistance.
