Briefly...

If your music is all written in the treble clef: it has been transposed and all you have to do is play what you see.

If much of your music is in the bass clef: it has not been transposed. You will need to transpose it up an octave and a tone. And if the part includes chord symbols, you need to transpose them up a tone.

If your part is in A, any non-transposing instruments will be in G.

You might find the expressions "concert pitch" and "guitar part" useful.

"Music in A major for tenor sax" exists, but "Music for tenor sax in A major" doesn't. There's no such thing as a tenor sax in A major.

In keys like A and E concert, which are so comfortable for beginners on the guitar, the tenor sax has to play in B and F# respectively; the alto in F# and C#.

If your music is all written in the treble clef it has been transposed and all you have to do is play what you see.

If much of your music is in the bass clef: it hasn't been transposed. You will need to transpose it up an octave and a tone, including any chord symbols.

If your part is in A, any non-transposing instruments will be in G.

The expressions "concert", "concert pitch" and "guitar part" might be useful. Do you know if it's a guitar part you're looking at?