Does a +1/+1 counter remove a -1/-1 counter?
121.3. If a permanent has both a +1/+1 counter and a -1/-1 counter on it, N +1/+1 and N -1/-1 counters are removed from it as a state-based action, where N is the smaller of the number of +1/+1 and -1/-1 counters on it. See rule 704.


Both counters will be removed as a state-based action (N=1). Your creature will be able to block and attack.