Leona is a Tok'ra. Leona is the host name and Somas is the Tok'ra's name.
The pair bond between Leona and Somas is unusually strong as both held a deep friendship with Somas' previous host Samara, who died prematurely. Their mutual sorrow over Samara's death and following despite struggle for survival paired these two together in direr circumstances through their grief.
Leona and Somas both have limited patience for the Tok'ra high council and prefer to spend their time scouting plant both by stargate and by ship. Their written reports are concise though their verbal ones are less so, generally due to Leona's influence. The high council seems happy to keep them busy with a never ending supply of planets to explore that is generally useful and always out of the way of critical, deep cover Tok'ra missions.