It means "we lost the game". The sentence is in the passive voice, which means that the actor, the one who is doing the action, is given at end of the sentence. You can identify these kind of sentences from the usage of the "by" preposition. By whom something was done => "beating was done by the other team" The sentence "We were narrowly beaten by the other team." if turned into the active voice would be "The other team narrowly beat us."

We lost. You have to take the sentence apart. In this sentence, "narrowly" (which means just slightly or barely) is an adverb describing "beaten" (which means to have lost). When you are "beaten by" someone it means that "you lost to them". So, the sentence can be shortened to "We lost to the other team.". You can then start adding words back in and changing them to what was in the original sentence. "We were just slightly beaten by the other team.". "We were narrowly beaten by the other team.".

"We almost got beaten by the other team" means like they hardly won the match there is an expression of having hard time to beat the other team and win.

It means 'we won the game', since 'narrowly' is similar to 'nearly'.