Does "pants" more commonly mean "trousers" or "underpants"?
In the UK "Pants" typically refers to underwear.
(Where it is also a slang term for "bad". As in "That's pants".)
In other parts of the world, notably the USA, "pants" refers to trousers.
In US usage pants means trousers.
In UK usage pants means underpants.
The popularity of US films and TV programmes means that most English speakers are likely to have some awareness of the US usage and will correctly understand phrases that use pants to mean trousers.