Well, you have good percentage in 10th, 12th and B.Tech. But if you are planning to pursue MS from UK or Germany after your completion of B.Tech then there is an entrance test in order to get admission in postgraduate. Entrance tests are TOEFL(Test Of English as a Foreign Language), IELTS(International English Language Testing System),Cambridge CAE (Certificate of Advanced English), CPE (Certificate of Proficiency in English), PTE (Pearson Test of English) etc. You will have to score high in any of these examination to get admission in MS in UK or in any other country. IELTS and TOEFL both are main examinations. Its score are accepted in most of the countries for postgraduate programs. These Tests are to check your English knowledge.
About TOEFL exam:-
There will be four section in TOEFL exam - listening, reading, speaking and writing. Your skill will be tested in these area.
Time:- 4:30 Hours will be given to complete the exam.
About IELTS exam:-
This examination is conducted in two sessions, 1st session consists reading, listening and writing papers. For this, 2:30 hours will be given to complete the examination. In 2nd session there will be the test of speaking. So for these examinations you must have good knowledge in English in order to get high score.
You can checkout IndiaStudyChannel's comprehensive guide for study abroad in Germany
which will help you find complete information on best universities, admission procedure, visa application process, fees and cost of living, etc.