The thousands separator: a comma here, a point in the city
A thousands separator is the mark that splits a large number into groups of three digits. This site uses a comma: 1,250. Dutch shops use a point: 1.250.
Large numbers are easier to read in groups. So 1250 becomes 1,250 or 1.250, depending on the country. The mark between the groups is the thousands separator. It does not change the value. Both forms mean one thousand two hundred and fifty.
The decimal mark
The trouble is that the same two marks are also used for decimals. In English, 12.50 means twelve and a half. In Dutch, the same amount is 12,50. So a comma can separate thousands in one country and mark cents in the next.
The rule on this site
This site always uses the comma for thousands, and no rate has cents. So 1,250 on any page means one thousand two hundred and fifty euros. If you see a figure with a point in it, it came from somewhere else, perhaps your phone or an app, and it is worth a second look.
A safe habit
When unsure, write the figure back in words and ask. Words have no marks. The guide to euro figures lists every rate in digits and in words.