is there a way to "fix" the audio?

[zanzar]

i have this video my mom took with a tablet and the mic picked a lot of buzzing noise.
is there a way to clean it so i could hear the person speak more clearly ?

[jagabo]

Load it into Audacity and use the notch filter to remove 50, 150, 250, 350... Hz with a Q value of 15 or so (narrow range). Also boost Amplitude and reduce noise peaks.

[pandy]

As already advised to you can use notch filter (perhaps there is preset like 50Hz ground loop hum removal) or you can use general FFT filter where you can remove signal around 50Hz and 50Hz harmonics - i think you can safely remove everything bellow 160Hz, then 200, 250Hz and as seem this is rectified 50Hz sinewave then your next candidates are separated by 100Hz so 350, 450, 550 till around 1350Hz. Next step is audio normalization with perhaps compression to make speech more legible. I would also filter everything above 8000Hz - not much there, mostly noise.

btw i also recommend to convert your sample (stereo) to mono, conversion should be done in digital domain with 100% 100% mix - you will double signal level and slightly reduce noise - such content is usually anyway mono.