When composers create music they decide which accent beat pattern, the Meter they want the music to have.
They put the number of that Meter at the beginning of a piece of music as the Top Figure of The Time Signatures.
That number tells musicians how many beats are measured into each bar of music.
Another name for a bar is a measure.
There could be 2 or 3 or 4 or 5 or 6 or more beats in each bar.
The composer then decides which ‘note’ is to be the one-beat-note.
That one-beat note will use the walk movement pattern.
The other notes have to change their movement and word/song.
The one-beat note is like the one in charge. The ‘boss of the bar’.
The composer puts the figure of that boss–note underneath the top figure which makes it the Bottom Figure of The Time Signatures.