Gases and liquids are fluids, which can be moving or at rest (static), but remember that although the mass may be at rest, its particles, atoms and molecules are continually agitated.

Hydrostatics studies liquids at rest.

The pressure in a liquid increases with its depth.

A submerged object in a liquid at rest experiences, on each of its faces, a  force caused by pressure which increases with the depth and acts perpendicularly to each face, whatever the direction it is pointing in.

The forces which are caused by pressure on the faces of a submerged body, when the liquid is at rest,  have to be perpendicular to the surface as, if they weren't, the horizontal component of the force would move the liquid parallel to the faces.

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