A320 First Officer reported that during approach the aircraft descended below glide path and a speed warning annunciated. Flight crew conducted a go-around and returned to landing.

Narrative

We were flying the ZZZZZ arrival to ZZZ XXR. We were asked to provide our best forward speed on arrival. We slowed to 250 kts below 10K and then slowed to 210 kts at ZZZZZ1. We were cleared for the approach XXR passing ZZZZZ2. Approach asked us to maintain 170 kts until a 5-mile final. Prior to the turn on to the LOC the CA turned off the autopilot and stated he was going to NAV to the final approach course. After arriving on final the CA asked me to arm the LOC and LOC was captured. At that point the CA turned off the auto thrust. At approximately 2000 agl the CA called for flaps 3 APPR arm and managed speed. I did not understand the managed speed" and asked him to repeat what he said. I selected flaps 3 and armed the approach. We had the speed brake out and were descending to capture the glide path. We flew below the glide path and still had the speed brake extended. The CA asked again for managed speed; and I selected managed speed. At that point we received a "Speed; speed" warning and a "Glide path; glidepath" warning. The CA executed a go around at approximately 1000 AGL. We did not execute the go-around. I was coordinating with Tower for our climb out instructions and was asked why we executed a go around. We were told to fly 190 heading and maintain 3000 msl. The CA asked me to reprogram the approach. While reprogramming the approach XXR the CA asked for the after TO checklist. I read the after TO checklist and said the gear was up when it was down. We cleaned up the flaps on schedule as to not overspeed anything. We then continued for an uneventful approach and landing on XXR ZZZ."