Start with the half you came for
Jennifer — the forename. A Cornish development of Guinevere that stayed regional until the twentieth century, then conquered the English-speaking world — the most popular girls' name in America for most of the 1970s. Origin, meaning, spelling variants and the popularity curve, sourced.
Cunningham — the surname. A toponymic from Cunninghame in Ayrshire with a contested etymology, carried into Ulster in the seventeenth century and separately adopted as an anglicisation of Ó Cuinneagáin. How one spelling came to cover several distinct families.
The combined name. Why "Jennifer Cunningham" appears so often in records from the 1960s onward — a short essay in name arithmetic: peak-era forename × high-frequency surname.
People named Jennifer Cunningham. The disambiguation list — documented public figures sharing the name, each with sources, so you can find the one you meant.
Notable Cunninghams. The wider surname's roll-call, from mediaeval Scotland to the present day.
The short answer
Asked what the name means: Jennifer is generally glossed as "white/fair one" — a Cornish cousin of Guinevere; Cunningham is a place-name surname from Ayrshire whose meaning is genuinely uncertain, despite the folk etymologies. Asked why there are so many of them: between 1945 and 1995 Jennifer was rarely outside the top ten girls' names anywhere English is spoken, and Cunningham ranks among the most common surnames of Scotland and Ulster. The rest is multiplication.