This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is a square composition of the glyphs Latin Small Letter C, Latin Small Letter D. Its East Asian Width is wide. In bidirectional text it is written from left to right. When changing direction it is not mirrored. U+33C5 offers a line break opportunity at its position, except in some numeric contexts.
The Wikipedia has the following information about this codepoint:
The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the luminous efficiency function, the model of the sensitivity of the human eye to different wavelengths, standardized by the CIE and ISO. A common wax candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured.
The word candela is Latin for candle. The old name "candle" is still sometimes used, as in foot-candle and the modern definition of candlepower.