For Lufthansa's EFA ATPL Programme, you will need to speak German and/or Italian, French or Dutch. Any of them at a B2 Level, I believe that EFA slightly prefer students who can speak fluent German as they will end up in an airline where German is required to an extent, but it definitely does not hinder you chances of getting in EFA. As EFA also provides the option for them funding your ATPL and a job with the Lufthansa Group, the selection process is tough. The exams consist of electrical engineering, mechanical processes as well as heat and fluid dynamics. Then they will test your English; grammar and vocab. They will also hold an ADAPT test (aptitude test) to test your memory, multitasking and other cognitive skills. Don't forget math and logical skills. It is much more than what flight schools usually ask for.
I feel that if you are fluent in the topics stated above you could get past the first stage of the assessment.
If you are expecting to try out EFA within a year or two, I would suggest learning German to that required level of B2. The average time to reach that level is about 500–600 hours of study time which translates to about 6-8 months depending on your consistency. If you have the hang of learning other languages, then it may be shorter.
I assume that you have gone through their website regarding what comes in the exams and the stages of assesment, if not refer to the EFA website and look at their selection procedure.
I hope to join EFA but not any time soon. Good Luck!
This is all the info that I know about. If anyone would like to correct me, please feel free to.