What does it mean by 'the residue was taken up in solvent' in synthesis protocol? The below is a synthetic protocol I need to perform:

N-trifluoro acetoxy succinimide Synthesis
Trifluoroacetic acid anhydride was added to N-hydroxysuccinimide at 0 °C. The reaction was allowed to warm up to r.t. over 24 h. Then toluene (50 mL) was added and the volatile was removed in vacuo. The residue was taken up in DCM (15 mL) and the remaining solvent was removed in vacuo.

I don't quite get the last sentence. What does it exactly mean by 'taking up a residue in solvent'? Does it mean I just need to add 15 mL DCM to the reacting mixture?
Also, the second bit also gets me confused — if I put my mixture under vacuum, wouldn't all the solvents get sucked up? what would be the point of adding DCM if I am placing my mixture under vacuum immediately after adding DCM?
You add the DCM to the material left after removing the toluene and then evaporate it off under vacuum. The reason is to ensure that all the trifluoroacetic acid is removed as this would adversely affect the next reaction, and TFA is readily soluble in DCM.