How to understand certain protein names
For H3K9me1:


H3: name of the histone
K9: amino acid and position (K = lysine, position 9) of modification
me1: modification (me = methylation, ac = Acetylation), and number of modifications


So H3K9me1 means that the 9th residue (lysine) of histone H3 was monomethylated. Similarly H3K9Ac means that same residue was acetylated.

Wikipedia gives a decent explanation of the nomenclature of histone modifications, and there is also a more detailed table in Nature Structural &amp; Molecular Biology.