String (Data Type)
A piece of text. It has to be enclosed in quotation marks, and quotation marks inside the text itself must be escaped with a backslash (\).
Examples
{
"field_name": "You should not sleep here!"
}A plain piece of text.
{
"type": "apoli:execute_command",
"command": "give @s minecraft:iron_axe{display:{Name:'{\"text\":\"Brutal Axe\", \"italic\": false}'}}"
}A string holding a command, with escaped quotation marks inside it.