Shield
Requirements
In order to wield a Shield effectively, you must have a Strength of at least 1.
A Shield requires a free hand to wield.
Lack of Requirements
If you do not meet the requirements, you get no AC bonus from the shield.
Don / Doff
A Shield takes 1 Action to don / doff.
A Shield can be donned or doffed as part of another Action once per Round.
FAQ
If you have a shield in your Equipment and you make an Attack, you can choose to stow or wield that shield as part of that Attack.
If you have a shield in your Stash, you may take an Action to retrieve it and then also don it to wield it as part of that same Action.
Don means wield the shield rather than its typically meaning of wearing armor.