FPC cable contacts. Bottom vs Top and Bottom
The description is basically telling you which side the metallic contacts on the connector are located.


Contacts Top - means that the pads on your FPC need to be facing towards the top of the connector
Contacts Bottom - means the opposite, that the pads on the FPC face downwards
Contacts Top, Bottom - means literally both, there are contacts on both sides, so you can connect either way up.


In the case of the connector you are interested in (Datasheet), the terminals in the connector contact both the top and bottom sides of the FPC, which means that you can place the pads on your FPC on either side - it is up to you which one you choose.