Translation:Mrs. Tanaka is good at playing tennis.
It's the same as the English gerund (put -ing at the end of a verb to turn it into a noun/activity: swim > swimming. Sing > singing). You can do a similar thing with (~する)こと, but (~する)のが is easier to use.
(Caps and katakana for emphasis) I like playING tennis (私は)テニスをするノガ好きです。
I like eatING (私は)食べるノガ好きです。
Actually, -san is not always translatable in English. English speakers usually do not address their peers as "Mr. So-and-so" or "Ms. So-and-so". This is especially true among students. After having spent nearly half of my life in Japan, I suggest that it's best just to leave "-san" as is. Everybody who knows me here in Japan calls me "Wolk-san", not "Mr. Wolk", even when we are communicating in English. And I address them as "~san".
Tanaka is a surname, though, not a gender-neutral name, except in the sense that Japanese surnames don't vary for gender. In English, you normally can't use a surname without something in front of it, so I'd say you would need a Mr/Mrs/Ms/Miss in front of Tanaka, or leaving the -san in the English
Actually, English-speaking people use a surname without a title quite frequently. That is especially true of boys and men, who refer to each other by just their last name all the time. No boy ever called me by my first name in junior high or high school (unless they were asking for me on the phone), and I doubt that you will ever hear high school students calling each other "Mr." and "Ms", unlike in Japan, where everyone is a "~san", or occasionally "~kun". Teachers are always addressed as "~Sensei", never "~san".