It means they are not attached to their "parent" atom, and they are aloud to roam freely to move through the bulk structure.
The functional groups are written in the pictures attached. The first picture is aspirin. The functional groups are carboxylic group(O=COH), ester (O=COR), and aromatic group (benzene ring), where R is any hydrocarbon chain. The second picture is acetaminophen. The functional groups are amide group (O=CNHR), hydroxyl group (ROH) and aromatic group (benzene ring).

Actually Welcome to the Concept of the Ionic bonds.
Since Sodium (Na) is a cation and Chlorine (Cl) is a Anion, they both form a Ionic bond called as NaCl (common salt)
So answer is, Na and Cl