abstellen
to turn off
To switch off a device, engine, or machine, or take it out of operation.
Vergiss nicht, den Motor abzustellen, wenn du parkst.
Don't forget to turn off the engine when you park.

to turn off / put down
Loading your saved state.
to turn off
To switch off a device, engine, or machine, or take it out of operation.
Vergiss nicht, den Motor abzustellen, wenn du parkst.
Don't forget to turn off the engine when you park.

'Abstellen' is a separable verb. In a main clause, the prefix 'ab-' stands at the end of the sentence. In a subordinate clause or with an infinitive with 'zu', the verb is not separated.
Stell bitte die Musik leiser oder ganz ab.
Please turn the music down or off completely.
The object of the verb reveals the meaning. You 'abstellen' devices (engine, light) in order to turn them off. You 'abstellen' objects (bag, bicycle) in order to put them down. You 'abstellen' problems (undesirable situation, behavior) in order to end them.
Er hat sein Auto direkt vor der Einfahrt abgestellt.
He parked his car right in front of the driveway.
In the meaning 'ausschalten' (to switch off), 'abstellen' is often used with technical devices or supply lines. Typical phrases are: 'den Motor abstellen' (to turn off the engine), 'das Licht abstellen' (to turn off the light), 'das Wasser abstellen' (to turn off the water), or 'den Strom abstellen' (to cut off the electricity).
Wegen der Reparatur müssen wir das Wasser für eine Stunde abstellen.
Because of the repair, we have to turn off the water for an hour.
In an abstract, often formal meaning, 'abstellen' is used for negative things that you want to end. For example, you can 'einen Missstand abstellen' (put an end to an undesirable situation), 'einen Mangel abstellen' (remedy a defect), or 'schlechtes Benehmen abstellen' (stop bad behavior).
Die Geschäftsführung versprach, die Mängel in der Produktion abzustellen.
Management promised to remedy the defects in production.
In the meaning 'basieren auf' (to be based on), 'abstellen' is fixed with the preposition 'auf' and the accusative. This construction is typical of administrative or legal language.
Das Urteil stellt auf die Aussagen mehrerer Zeugen ab.
The judgment is based on the statements of several witnesses.
to insert / to begin / to use
'einsetzen' and 'abstellen' can both mean that a person is used for a task. 'Einsetzen' is more general: you use people or resources for a specific purpose. 'Abstellen' often sounds more official or organizational and means that someone is assigned to a duty or task, often temporarily. Learners may confuse the words because both occur in work and planning contexts. 'Einsetzen' is usually more neutral, while 'abstellen' puts more emphasis on assignment by an office, department, or management.

Für den Empfang wurde ein Mitarbeiter aus der Verwaltung abgestellt.
An employee from administration was assigned to the reception.
Beim Stadtfest setzt die Feuerwehr viele Helfer ein.
At the town festival, the fire department uses many helpers.