You are looking at the HTML representation of the YAML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the YAML format, set format=yaml.
See the complete documentation, or API help for more information. 
{
	"query": {
		"namespaces": {
			"-2": {
				"id": -2,
				"case": "first-letter",
				"*": "Media",
				"canonical": "Media"
			},
			"-1": {
				"id": -1,
				"case": "first-letter",
				"*": "Special",
				"canonical": "Special"
			},
			"0": {
				"id": 0,
				"case": "first-letter",
				"*": "",
				"content": ""
			},
			"1": {
				"id": 1,
				"case": "first-letter",
				"*": "Talk",
				"subpages": "",
				"canonical": "Talk"
			},
			"2": {
				"id": 2,
				"case": "first-letter",
				"*": "User",
				"subpages": "",
				"canonical": "User"
			},
			"3": {
				"id": 3,
				"case": "first-letter",
				"*": "User talk",
				"subpages": "",
				"canonical": "User talk"
			},
			"4": {
				"id": 4,
				"case": "first-letter",
				"*": "Project",
				"subpages": "",
				"canonical": "Project"
			},
			"5": {
				"id": 5,
				"case": "first-letter",
				"*": "Project talk",
				"subpages": "",
				"canonical": "Project talk"
			},
			"6": {
				"id": 6,
				"case": "first-letter",
				"*": "File",
				"canonical": "File"
			},
			"7": {
				"id": 7,
				"case": "first-letter",
				"*": "File talk",
				"subpages": "",
				"canonical": "File talk"
			},
			"8": {
				"id": 8,
				"case": "first-letter",
				"*": "MediaWiki",
				"subpages": "",
				"canonical": "MediaWiki"
			},
			"9": {
				"id": 9,
				"case": "first-letter",
				"*": "MediaWiki talk",
				"subpages": "",
				"canonical": "MediaWiki talk"
			},
			"10": {
				"id": 10,
				"case": "first-letter",
				"*": "Template",
				"canonical": "Template"
			},
			"11": {
				"id": 11,
				"case": "first-letter",
				"*": "Template talk",
				"subpages": "",
				"canonical": "Template talk"
			},
			"12": {
				"id": 12,
				"case": "first-letter",
				"*": "Help",
				"subpages": "",
				"canonical": "Help"
			},
			"13": {
				"id": 13,
				"case": "first-letter",
				"*": "Help talk",
				"subpages": "",
				"canonical": "Help talk"
			},
			"14": {
				"id": 14,
				"case": "first-letter",
				"*": "Category",
				"canonical": "Category"
			},
			"15": {
				"id": 15,
				"case": "first-letter",
				"*": "Category talk",
				"subpages": "",
				"canonical": "Category talk"
			},
			"102": {
				"id": 102,
				"case": "first-letter",
				"*": "Property",
				"canonical": "Property"
			},
			"103": {
				"id": 103,
				"case": "first-letter",
				"*": "Property talk",
				"subpages": "",
				"canonical": "Property talk"
			},
			"106": {
				"id": 106,
				"case": "first-letter",
				"*": "Form",
				"canonical": "Form"
			},
			"107": {
				"id": 107,
				"case": "first-letter",
				"*": "Form talk",
				"subpages": "",
				"canonical": "Form talk"
			},
			"108": {
				"id": 108,
				"case": "first-letter",
				"*": "Concept",
				"canonical": "Concept"
			},
			"109": {
				"id": 109,
				"case": "first-letter",
				"*": "Concept talk",
				"canonical": "Concept talk"
			},
			"420": {
				"id": 420,
				"case": "first-letter",
				"*": "Layer",
				"canonical": "Layer"
			},
			"421": {
				"id": 421,
				"case": "first-letter",
				"*": "Layer talk",
				"canonical": "Layer talk"
			}
		}
	}
}