When running android list targets, I got ABIs: armeabi-v7a
what does this mean? please provide the internal details of how this is used?
ARM is a type of instruction set for CPUs usually used on mobile devices.
armeabi stands for ARM embedded application binary interface, it means the image that the android is running is built with EABI support. armeabi-v7a code is extended armeabi code which can contain extra CPU instructions, and have support for hardware floating point operations.
You'll find a more detailed answer at: Why use armeabi-v7a code over armeabi code? link.