2D　magnets　represent　material　systems　in　which　magnetic　order　and　topological　phase　transitions　can　be　observed.　Based　on　these　phenomena,　novel　types　of　computing　architectures　and　magnetoelectronic　devices　can　be　envisaged.　Unlike　conventional　magnetic　films,　their　magnetism　is　independent　of　the　substrate　and　interface　qualities,　and　2D　magnetic　properties　manifest　even　in　formally　bulk　single　crystals.　However,　2D　magnetism　in　layered　materials　is　rarely　reported　often　due　to　weak　exchange　interactions　and　magnetic　anisotropy,　and　low　magnetic　transition　temperatures.　Here,　the　electron　spin　resonance　(ESR)　properties　of　a　layered　antiferromagnetic　CrSBr　single　crystal　are　reported.　The　W-like　shape　angular　dependence　of　the　ESR　linewidth　provides　a　signature　for　room　temperature　spin-spin　correlations　and　for　the　XY　spin　model.　By　approaching　the　Neel　temperature　the　arising　of　competing　intralayer　ferromagnetic　and　interlayer　antiferromagnetic　interactions　might　lead　to　the　formation　of　vortex　and　antivortex　pairs.　This　argument　is　inferred　by　modeling　the　temperature　dependence　of　the　ESR　linewidth　with　the　topological　Berezinskii-Kosterlitz-Thouless　phase　transition.　These　findings　together　with　the　chemical　stability　and　semiconducting　properties,　make　CrSBr　a　promising　layered　magnet　for　future　magneto-　and　topological-electronics.