A "separate bassinet" refers to a bed for babies that is detached or not connected to another piece of furniture. It provides a separate sleeping space for the baby that is separate from the main bed. Full definition
The carefully worded recommendation calls for the mother and infant to be in «close proximity,» which could be a separate bassinet or a small crib that attaches to the bed. (articles.chicagotribune.com)
Have him sleep in a separate bassinet, crib, or cradle that is close to your bed in the same bedroom, but not in your bed. (verywellfamily.com)
Secondly the stroller seat converts into a bassinet so no need to buy a separate bassinet for your new born. (bestbabydollstrollerreviews.com)