Once you have worked out the speed (tempo) of the music, you need to work out how the beats are organized and divided into regular groups or bars = The Time Signature
The majority of music has four beats, with the greatest stress falling on the first beat of the measure/bar = downbeat.
A waltz is in 3/4=three beats in the bar.
Especially in film music and news themes, more elaborate time signatures are common as the composer works to fit with the action in the film.
Five or seven beats are not uncommon
Marco Beltrami’s Film Score to Underworld Evolution starts in 7/8. This is an excerpt from the scene “Truckin”.