Questions & Answers about Hún klifrar varlega niður aftur.
Klifrar is the 3rd person singular present form of the verb klifra (to climb).
Because the subject is hún (she), Icelandic uses:
- ég klifra = I climb
- þú klifrar = you climb
- hún klifrar = she climbs
So -r here is part of the present-tense ending for you/he/she/it with this verb pattern.