This method returns all the objects you have in your salesforce account and it does not require any parameter.
// Sample Response
[
{
"activateable": false,
"createable": false,
"custom": false,
"customSetting": false,
"deepCloneable": false,
"deletable": false,
"deprecatedAndHidden": false,
"feedEnabled": false,
"hasSubtypes": false,
"isInterface": false,
"isSubtype": false,
"keyPrefix": null,
"label": "Accepted Event Relation",
"labelPlural": "Accepted Event Relations",
"layoutable": false,
"mergeable": false,
"mruEnabled": false,
"name": "AcceptedEventRelation",
"queryable": true,
"replicateable": false,
"retrieveable": true,
"searchable": false,
"triggerable": false,
"undeletable": false,
"updateable": false,
"urls": {
"rowTemplate": "/services/data/v47.0/sobjects/AcceptedEventRelation/{ID}",
"defaultValues": "/services/data/v47.0/sobjects/AcceptedEventRelation/defaultValues?recordTypeId&fields",
"describe": "/services/data/v47.0/sobjects/AcceptedEventRelation/describe",
"sobject": "/services/data/v47.0/sobjects/AcceptedEventRelation"
}
},
{another record},
{another record},
]