If you see the measurements EBC or SRM on the side of your beer bottle what do they tell you about the beer?

EBC is the European Brewery Convention. Although some have suggested it could mean "Estimating Beer Colour"! It is used as a measure of the beer's colour. The higher the number, the darker the beer. The website below has a relevant colour chart.

https://www.saveur-biere.com/en/magazine/brewing/4/white-blonde-ruby-brown-beer-in-every-colour/58

Likewise, SRM refers to the Standard Reference Method of colour assessment from the American Society of Brewing Chemists. This method uses a device to measure the colour of the wort or beer.

https://beerandbrewing.com/dictionary/xizZHSE4me

Hmmm... from my student days in analytical chemistry, I knew Beer's law (A=abc) was more than just a memorable name!