der Pool
pool
An artificial basin filled with water and used for swimming or bathing; a swimming pool.
An heißen Tagen springen wir zur Abkühlung in den Pool.
On hot days, we jump into the pool to cool off.

pool
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pool
An artificial basin filled with water and used for swimming or bathing; a swimming pool.
An heißen Tagen springen wir zur Abkühlung in den Pool.
On hot days, we jump into the pool to cool off.

'Pool' is a word from English. The meanings in German are very similar to those in English, so you do not have to learn a completely new logic.
Unser Hotel hat einen großen Pool mit einer Wasserrutsche.
Our hotel has a large pool with a water slide.
You can easily tell which meaning is intended from context. If it is about water and swimming, it means the swimming pool. If it is about work and personnel, it refers to collected resources.
Im Sommer verbringe ich jede freie Minute im Pool.
In summer, I spend every free minute in the pool.
Pay attention to the difference between accusative and dative. Movement toward the pool is expressed with 'in den Pool' (into the pool), while staying or doing an activity in the water is described with 'im Pool' (in the pool).
Die Kinder springen begeistert in den Pool.
The children excitedly jump into the pool.
In the meaning 'Sammlung von Ressourcen' (collection of resources), 'Pool' is often used with the preposition 'an' or 'von'. A common phrase is also 'auf einen Pool zurückgreifen' (to draw on a pool).
Die Firma hat einen Pool an Dienstwagen.
The company has a pool of company cars.
stock / inventory
'der Bestand' and 'der Pool' can both refer to an existing quantity or collection. 'Bestand' describes more what is available in a warehouse, a collection, or a system. 'Pool' refers to a group of people or resources from which something can be selected or used when needed. The words can be confused when talking about available things. 'Bestand' fits better when checking or managing a quantity, while 'Pool' fits better when several options are available for a shared purpose.

Für den Kurs gibt es einen Pool von Lehrkräften, die einspringen können.
There is a pool of teachers for the course who can step in.
Wir prüfen den Bestand an Ersatzteilen vor der Reparatur.
We check the stock of spare parts before the repair.