The parliament has 14 days to try and get a different (or the same) person elected with the total majority (>50% of votes). If they can not get a person elected with more than 50% of the votes during those 2 weeks they then can elect a person with a relative majority. Since Merz was only short a couple votes they will probably still elect him and this was just a demonstration of power from the SPD since they barely have the 50% in the parliament if both parties combine their votes.
The parliament has 14 days to try and get a different (or the same) person elected with the total majority (>50% of votes). If they can not get a person elected with more than 50% of the votes during those 2 weeks they then can elect a person with a relative majority. Since Merz was only short a couple votes they will probably still elect him and this was just a demonstration of power from the SPD since they barely have the 50% in the parliament if both parties combine their votes.