In the PHB, on page 193, the Use an Object action is described:
Use an Object
You normally interact with an object while doing something else, such as when you draw a sword as part of an attack. When an object requires your action for its use, you take the Use an Object action. This action is also useful when you want to interact with more than one object on your turn
But what exactly is considered an object?
More specifically:
Is an arrow an object? Are weapons, armors, and shields objects?
Best Answer
An object is any physical thing that is not a creature:
The above description lists creatures, objects, and points in space as the 3 distinct, mutually exclusive types of targets. Note that spell effects are not physical things, and so are not objects, creatures, or points in space, though spell effects can affect, create, or share space with one or more of them.
A creature is anything that can take any (or at least most) of the general actions. All creatures fall into the categories of either Player Character or Monster:
So, you can also say that anything besides the PCs that isn't covered by the MM is an object.
This means that arrows, weapons, armor, and shields are, in fact, objects. NOTE: using some objects have more specific actions, so the "Use An Object" action you quoted does not apply. This is case for arrows (ammunition property of weapons and the attack action), weapons (the attack action), and armor and shields (donning and doffing and armor class). If you do something unconventional with one of these objects, such as using a sword as a lever to crank a wheel, the "Use An Object" action would apply.