It's a fund with a portfolio mix that's based on the kind of lifestyle a particular investor would want to match.
This mix generally considers factors such as current income levels, current assets / savings, risk tolerance of the individual, years until retirement or any other major stage of life, type of progress (aggressive growth, value, strategic growth, etc,..)
For example,
investors in their 20's could go for aggressive growth funds, investors in their 30's and 40's could go for moderate to conservative growth funds, and investors nearing their retirement may feel comfortable with conservative growth funds, though it's a personal choice of each and every individual investor.