Recovery 'E' Drive ????? Inspiron 1545

HI i have been checking some posts on this but i am now lost, i tried to do a system back up and this failed as there was not enough space on the E recovery drive....

i Just used the backup status and configuration and basically pressed back up now....

Can i just delete anything that is on that drive ???? I have no idea what is on there ???

what is it for ???      if there is supposed to be files on there, what needs to be on there and what can i delete ???

Please help in Lamens term. i am using a dell inspiron 1545.

Many Thanks

Dazmac7