MX Player Codec (ARMv7) is exactly what its name suggests: a codec pack for Android devices with ARMv7 VFP cores, exclusively for use with MX Player (also available on Uptodown).
It's important to note that this app can't do anything by itself. MX Player Codec (ARMv7) is an ADD-ON to MX Player, which you have to install separately beforehand. Once you do, you can use MX Player to play any kind of movie file.