Translation:My parents are sabras, so I'm second generation.
Although "Sabra" means a native Israeli, it's also the Hebrew name of the prickly pear cactus. Native Israelis are called "prickly pears" because like the prickly pear, they are tough, thorny and spiky on the outside, while on the inside they have a very sweet and tender disposition
Yeah, I was arguing with a friend about this. My parents are immigrants, and I consider myself second-generation. But my friend insists that I'm first-generation (making my parents zeroth-generation?!). Wikipedia says both usages are okay: https://en.wikipedia.org/wiki/Immigrant_generations#First_generation
The wikipedia article, mentioned above by synchroneity, has a good Oxford Dictionary reference that may help: http://www.oxforddictionaries.com/us/definition/american_english/first-generation?q=first+generation
Based on the article referenced by synchroneity, it seems the definition depends on whether we're using the US definition. Since DL uses American English, I'd say the default is that the immigrant generation that became citizens is the "first generation". So, the person in the above sentence is third generation.
See the second paragraph of that section: "This ambiguity is captured and corroborated in The Oxford English Dictionary's definition of "generation":
...designating a member of the first (or second, etc.) generation of a family to do something or live somewhere; spec. designating a naturalized immigrant or a descendant of immigrant parents, esp. in the United States.... (OED definition of "generation," section 6b., the term "first generation" is used to refer to foreign-born residents (excluding those born abroad of American parents).[ "Nation's Foreign-Born Population Nears 37 Million". Press Release. U.S. Census Bureau. Retrieved 31 January 2012.]
I recently read George Takei's graphic novel "They Called Us Enemy" (which I thought was great, by the way), and in it he explained "There were issei (1st-generation), who had come to American from Japan...nisei (2nd-generation), who were born in this country...and even sansei (3rd-generation), the children of nisei parents." This is interesting to me because of what you said earlier about the term "first generation" applying to the generation that became citizens. Takei explains that his father (who has been born in Japan) was not allowed under US law to become a citizen. The law has changed now, so it's moot in a way, I just thought it might interest you to know that Takei supports your position (though, and I think I agree with him, perhaps it should be dependent on residency and not citizenship).
First gen (when referring to citizenship) are the first generation to be born in that country. Third generation implies they are the third gen to be born there, not lived or held citizenship there. Some dictionaries have both definitions, this is wacky and leads to confusion. Outside of Israel, it only works differently if you specify = I'm the third generation to live in X country, or when referring to something not related to origin/location = I'm the third generation of women in my family to have red hair (not true, I'm first at something!)...
In Israel, if you are referring to something like sabras, it has to be related to birth. A sabra by definition is a Jew born in Israel.