Panda Video Compress reduces the file size of videos on an Android device. The situation it addresses is common and specific, which is a recording that is too large to send by email, message, or upload without waiting a long time or being refused outright.
Compression here means re-encoding at a lower bit rate, resolution, or both, and it is worth being clear that this is lossy rather than reversible, so the output is a new file and the original should be kept until the result has been checked. Several preset levels are offered rather than exposing encoder parameters, which is the right choice for the audience, since the useful question is how small the file needs to be rather than which codec settings achieve it. Batch processing handles a set of files in one operation, which matters because compressing individually is the tedious part, and trimming is included so that removing the unwanted opening and closing seconds can be done in the same step, which frequently reduces size more than any encoder setting would. The processing happens on the device, so nothing is uploaded, and the time taken depends on the length of the video and the hardware encoder available, which varies considerably between phones.
Anything requiring precise control over encoding will find the preset approach limiting. For its intended use, which is making a file small enough to send without visibly ruining it, the presets are the reason it is usable.