The form suggested in another answer:
The language I have been speaking even before learning English is Unique
is not correct. That should be
The language [that] I was speaking before learning English is unique.
if "unique" is meant to describe that other language. However, if "Unique" the the name of an (imaginary) laguage, one might say:
The language [that] I was speaking before learning English was Unique.
The language [that] I was speaking before learning English was Russian.
In the original question the form "The language I speak before learning English" is incorrect because "speak" is in the present tense, but "before" indicates a past event, so "spoke" is needed. This is because one may not use a simple present tense to describe a past action, and this describes the language that was spoken at a past time. The latter verb "was" must agree. This construction can be ambiguous, and additional context must clarify that: "The language I spoke before learning English was Greek. Now I speak both languages." or "The only language i spoke before learning English was Greek."