The acknowledgment is for any particular individuals that you wish to give credit to in your dissertation. This is generally those who helped support your research.

Note that if you had a research site you should not name the site or individuals at the site in the acknowledgement as that will reveal your research site.

Most researchers dedicate the dissertation to close friends/family members/spouses/partners. For inspiration on how to frame the dedication and acknowledgment, you may wish to read other dissertation and publications.