abholen
to pick up
To meet someone at an agreed place and take them along from there.
Ich fahre zum Bahnhof, um meine Schwester abzuholen.
I'm driving to the train station to pick up my sister.

to pick up
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to pick up
To meet someone at an agreed place and take them along from there.
Ich fahre zum Bahnhof, um meine Schwester abzuholen.
I'm driving to the train station to pick up my sister.

'Abholen' (to pick up) is a separable verb. The prefix 'ab' goes at the end of the sentence in a main clause. In a subordinate clause, the whole verb goes at the end.
Holst du mich heute Abend vom Training ab?
Are you picking me up from training tonight?
The verb 'abholen' (to pick up) always needs an accusative object: the person or thing being picked up. The place from which someone or something is picked up is often given with 'von' or 'an' (+ dative).
Kannst du bitte die Kinder von der Schule abholen?
Can you please pick up the children from school?
The figurative meaning is modern and is often used in education, marketing, or politics. It almost always occurs in the fixed structure 'jemanden dort abholen, wo er/sie steht' (to meet someone where he/she is).
Eine gute Präsentation holt das Publikum bei seinem Wissensstand ab.
A good presentation meets the audience at their level of knowledge.
to reach
'erreichen' and 'abholen' can both have to do with a place you arrive at. 'erreichen' only means that you arrive at a destination, for example the train station or home. 'abholen' means more: you go to a place, meet someone there or collect something, and usually bring them or it with you. So you can reach a place without picking anyone up there. Learners often confuse the words when talking about routes and appointments. Remember: you reach the train station; you pick up a person or a package.

Nele holt ihre kleine Schwester nach dem Training ab.
Nele picks up her little sister after training.
Wegen des Staus haben wir den Bahnhof erst kurz vor acht erreicht.
Because of the traffic jam, we only reached the train station shortly before eight.