Assuming you mean more than the difference between the singular and plural masculine form adjectives, that is a big topic ! 

Not sure it can be covered here, except by suggesting the lesson on this site,  or on Laura Lawless site and if that doesn’t help, to look for others on the net.

Have linked one external site, but if you prefer a video lesson, there are many good ones available on YouTube. 

For tricky concepts, I think it is always worth seeking different approaches to the explanation - the repetition is beneficial, and the different approaches can often add a bit more understanding. 

Tout/tous/toute/toutes = Everything/all (of them)/whole/completely in French 

https://www.lawlessfrench.com/grammar/tout-toute-tous-toutes/

https://www.frenchtoday.com/blog/french-grammar/tout-french-pronunciation-tous/