The time it takes to don or doff armor depends on the armor's category. A shield can be donned or doffed as an action.
Don or Doff a Shield
ActionPHBp. 1462014SRD
Raw data
{
"srd": true,
"name": "Don or Doff a Shield",
"page": 146,
"time": [
{
"unit": "action",
"number": 1
}
],
"__prop": "action",
"source": "PHB",
"entries": [
"The time it takes to don or doff armor {@table Getting Into and Out of Armor; Donning and Doffing Armor|phb|depends on the armor's category}. A {@item shield|phb} can be donned or doffed as an action."
],
"basicRules": true,
"reprintedAs": [
"Don or Doff a Shield|XPHB"
]
}