This answer applies in the context of tourism/voyages. There are different meanings in different contexts. The noun 'travel' refers to the action of traveling in general, not a single voyage, and so it is normally uncountable. And it's not a synonym for 'journey' or 'trip'. So we don't say "a travel". A typical example might be "Travel is more difficult now because of Covid." 'Journey' and 'trip' refer to specific voyages. Technically 'journey' is one single voyage, whereas 'trip' is a series of voyages. So for example "Next week I will visit the UK. My journey from Italy to the UK includes a flight from Rome to London. I will return via Bristol airport to Rome. So my trip includes three airports." Both plural forms, 'journeys' and 'trips' CAN be a synonym for 'travels'. "Marco Polo visited many countries on his travels/journeys/trips." I said "technically" above because in reality we don't always follow these rules. Follow them if you are doing an exam...be a bit more flexible if you are communicating with native speakers.