I see this library (armeabi) many times when I explore open sources.
I net searched for an explanation of it, but all the results I found are talking ABOUT it and not defining it.
What is this armeabi and why are they using it in Android applications?
Android devices have CPUs. Many of those CPUs are based on the ARM architecture, while some are based on x86, and a few others are based on other stuff like MIPS.
Some Android apps use the Native Development Kit (NDK) to create C/C++ code to link into their app. C/C++ code needs to be compiled for a specific CPU architecture. The NDK places the version of the C/C++ code compiled for each architecture into an architecture-specific directory. One of those directories is armeabi/, which is for a generic ARM CPU. There is also armeabi-v7/ (for an ARM v7-compatible CPU), x86/ (for x86 CPUs), etc.