Moves the sum of cell 0 and cell 1 to cell 2
,>, Takes input in cell 0 and 1
[>+<-] Moves cell 1 to cell 2
< Moves back to cell 0
[>>+<<-] Adds cell 0 to cell 2
>>. Moves to cell 2 and prints

;:# ,>,[>+<-]<[>>+<<-]>>.
Minimised form in comment