The particle から (KARA) is used to indicate the origin, such as a place, time from which an action takes place, a list of events, etc. It is often paired with the particle まで (MADE) to create the structure "from... to/until..."
授業は毎日8時半から始まります。
Jugyou wa mainichi hachiji han kara hajimarimasu.
The class starts at 8:30 AM every day.
台所から変な匂いがします。
Daidokoro kara hen na nioi ga shimasu.
A strange smell is coming out from the kitchen.
2.
から (KARA) expresses the passage of time (since / after doing) in the structure "verb in -TE + KARA."
田中さんに最後に会ってから3年になります。
Tanaka san ni saigo ni atte kara sannen ni narimasu.
It’s been three years since I last met Mrs. Tanaka.
With the same structure (-TE + KARA), the particle から can also indicate that one action begins after another one has been finished (literally one can think like this "from one action (から), I start another one). This is why it can often be translated as "after doing..."
お風呂に入ってからテレビを見ました。
Ofuro ni haitte kara terebi o mimashita.
I watched TV after I took a bath.
3.
から (KARA) can define the raw material used to make something (to be made from).
おもちは米から作ります。
Omochi wa kome kara tsukurimasu.
Mochi is made from rice.
4.
The particle から (KARA) designates the agent (the person at the origin of an action) in a passive structure. Note that the particle に (NI) is more frequent in that case.