The answer to this question will depend on the piece of music to which it applies, however there are several different textures which you must know for GCSE music:
Unison - this is where all singers or instruments are playing the same melody with the same rhythm, though not necessarily at the same pitch
Monophonic - there is only one line of music with no accompaniment or melody
Homophonic - the music will sound together, there may be a solo line with a chordal accompaniment or all the parts may have the same rhythm but with different notes
Heterophonic - the same melody is played by several different instruments but one line may be more ornamented than the others
(I would normally ask to listen to the piece of music that the question is based on to help distinguish the texture - these are always available with past papers)