
umfallen
to fall over
To fall sideways or downward from a standing or upright position.
Durch den starken Wind ist der alte Baum im Garten umgefallen.
Because of the strong wind, the old tree in the garden fell over.
to fall over / faint / cave in
Loading your saved state.

to fall over
To fall sideways or downward from a standing or upright position.
Durch den starken Wind ist der alte Baum im Garten umgefallen.
Because of the strong wind, the old tree in the garden fell over.

to faint
Colloquial for 'to faint' or 'to lose consciousness'.
Ihr wurde in der Hitze plötzlich schwarz vor Augen und sie ist fast umgefallen.
In the heat, her vision suddenly went black and she almost fainted.

to cave in
Colloquial and figurative for 'to suddenly change one's opinion or decision', often because of pressure; to give in.
Zuerst war er strikt dagegen, aber als alle auf ihn einredeten, ist er dann doch umgefallen.
At first he was strictly against it, but when everyone kept talking at him, he caved in after all.
'Umfallen' (to fall over/faint/cave in) is a separable verb. The prefix 'um-' goes to the end in a main clause. In subordinate clauses and in the infinitive, the verb stays together.
Pass auf, dass das Glas nicht umfällt!
Be careful that the glass doesn't fall over!
Since 'umfallen' (to fall over/faint/cave in) describes a change of state or position, the perfect tense is always formed with the auxiliary verb 'sein' (to be). So it is 'ich bin umgefallen' (I fell over/fainted/caved in), not 'ich habe umgefallen'.
Die Vase ist vom Tisch gefallen und umgefallen.
The vase fell off the table and fell over.
The literal meaning (m01) can refer to people and objects. The two colloquial meanings 'ohnmächtig werden' (to faint) (m02) and 'Meinung ändern' (to change one's opinion) (m03) always refer only to people.
Der Radfahrer ist gestürzt, aber zum Glück nicht umgefallen.
The cyclist crashed, but luckily didn't fall over.
When someone 'umfällt' (caves in) because they change their opinion, it often has a negative connotation. It implies that the person is weak, does not have a firm position, or gives in to pressure.
Er hat lange Widerstand geleistet, aber am Ende ist er doch umgefallen und hat zugestimmt.
He resisted for a long time, but in the end he did cave in and agreed.
to fall / overthrow
When someone falls from an upright position, both stürzen and umfallen can be used. Stürzen emphasizes the forceful or uncontrolled fall, whereas umfallen emphasizes the loss of the upright position, often to the side. Use stürzen to describe the process and umfallen to describe the change in position.

Der Läufer verlor das Gleichgewicht und fiel zur Seite um.
The runner lost his balance and fell over to the side.
Der Läufer stolperte über einen Stein und stürzte heftig auf den Weg.
The runner tripped over a stone and fell hard onto the path.