On a T-s plot, when moving from left to right the isobar represents heat addition at constant pressure. When moving from right to left, the isobar represents heat removal at constant pressure.
Boiling, condensation, superheating, reheating and transport in pipes are approximated as isobaric. Constant pressure heating/ cooling might be reasonably assumed in heat exchangers. Some more detailed calculations might tackle pressure losses of up to 7-bar in pipes.
Draw two isobars with pressures of 1.2 bar and 17 bar. Highlight each isobar in turn and note how the left hand side is practically indistinguishable from the saturated water line (there are differences, but they cannot be seen at this scale).
For either isobar move the POI from left to right, increasing entropy. One notes (1) as stated above, we started moving very close to the saturated liquid region (IAWPS region 1) (2) in the wet steam region (IAWPS region 4) increasing entropy results in higher dryness fraction and enthalpy but the temperature is constant (3) to the right of the "g-part" of the saturation curve, POIs are now found in the superheated steam region (IAWPS region 2) and enthalpy and temperature increase.
Recall that in practice an increase in entropy corresponds to heat addition.