An educated guess would be about 25-30k in burst potential but about half that in sustainable throughput. However there are a lot of other factors to consider.
Type of healing (raid or tank healing). Raid size. The particular encounter.
Judging by this characters stat prioritization and spec I would assume they are primarily a tank healer (emphasis on mastery and 3/3 Nature's Bounty). Also judging by their spec I'd assume they are also in a 25 man raiding environment (Glyph of Innervate and absence of Nature's Cure).
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.