So when asking questions, please try to be as detailed as possible, and even insert a quote of the section you are uncertain about. Your above question is very ambigous, and can have a variety of answers.
As your question is posted in the Actuarial Models section, I am assuming you are referring to what is meant when a group of lives is considered homogenous. This means that the lives can be considered identical with respect to the factor of interest I.e. mortality. Thus the group of lives face the exact same risks and have the same forces of mortality, and thus the same survival functions.
If I have not answered your question I do apologise, however this is how I interpreted it. Feel free to comment a more detailed explanation of what you are confused about.