This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+271B forms with similar adjacent characters prevents a line break inside it.
The Wikipedia has the following information about this codepoint:
A cross is a compound geometrical figure consisting of two intersecting lines, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a saltire in heraldic terminology.
The cross has been widely recognized as a symbol of Christianity from an early period in that religion's history. Before then, it was used as a religious or cultural symbol throughout Europe, in western and south Asia (the latter, in the form of the original Swastika); and in Egypt, where the Ankh was a hieroglyph that represented "life" and was used in the worship of the god Aten. The effigy of a man hanging on a cross was set up in the fields to protect the crops. It often appeared in conjunction with the female-genital circle or oval, to signify the sacred marriage, as in Egyptian amulet Nefer with male cross and female orb, considered as an amulet of blessedness, a charm of sexual harmony.