ECTS stands for "European Credit Transfer System". You collect these credits when completing courses and exams. Take for example a course of 5 ECTS credits: The number of ECTS credits is calculated from the effort that more or less is required in your course. 1 ECTS credit corresponds on average to a workload of 25 hours per semester. The workload includes the preparation, the course unit itself and the follow-up as well as the exam preparation.

One more detail: 
The "European Credit Transfer System" makes higher education within Europe more comparable. It aims at enabling students with a higher education degree from institution A to continue their higher education at institution B.

We wish you lots of succcess in your studies!