Short summary. The 0.5 mm sea level rise due to ice melting in July is dramatic but you need to compare it with the rest of the year. July is usually the top month for ice loss. In the winter the Greenland ice sheet gains ice through snowfall, so you need to look at the balance between losses and gains.
Also you need to compare it with previous years. It’s actually not quite enough of a melt so far to beat the 2012 record. The Arctic sea ice minimum this year is also not expected to be as low as the 2012 minimum. .
This is nothing to be scared of. Just an unsurprising increased melt, after a previous year when there was so much snow that Greenland actually gained ice due to heavy winter snowfall in 2017–8