It has a lot of translations!
You can't tell from just one word, that's why both entrance and ticket are accepted in this exercise.
But in real life, you'll know from context. The same as you know from the baseball player swung the bat hard that the bat is an object, and from the bat flew soundlessly through the night that the bat in this case is an animal.
If you're in Spain, then this is the common usage:
la entrada = entrance ticket (like to a museum, gallery, concert etc.)
el billete = transport ticket (like for a bus, metro, train etc.)
el boleto = scratchcard/lottery ticket
In Latin America, el boleto seems to be used for the entrance ticket, but otherwise I'm not very familiar with LA usage, so maybe a native LA speaker or someone with enough knowledge about this could chime in. :)