unvoiced aspirated bilabial plosive.
Usually called a stop these days rather than a plosive, in English anyway.
unvoiced :- sounds made without the vocal cords vibrating. In English, /p, t, k, f, T, s, S/ are voiceless. /b, d, g, v, D, z, Z/ are their voiced counter parts.
aspirated :- produced with a slight puff of air (an aitch). Hold your hand in front of your mouth and say the word 'top'. Feel a little puff of air after the /t/? Now say 'stop'. Where'd it go? The /t/ in 'top' and the /t/ in 'stop' are not the same sound. The former is aspirated and the latter unsapirated.
bilabial :- a stop made with both the lips closed, e.g., /p, b, m/. Different from labio-dental: /f, v/. Known as the place of articulation: bilabial, labio-velar, alveolar, dental, interdental, retroflex, palatal, velar, uvular, pharyngeal, etc.
stop :- stopping the flow of air in the vocal tract. A bilabial stop /p, b/ is made by stopping the air at the lips. Stops: /p, b, t, d, k, g/. Known as the manner of articulation: stops, fricatives, affricates, nasals, etc.
So an unvoiced aspirated bilabial stop would be /pʰ/ (or /ph/ with the h elevated and slightly smaller if your Unicode isn't working).
The difference between bilabial and labio-dental is an interesting one and leads to all sorts of confusion between anglophone and non-anglophone speakers: e.g., the {f} in futon is pronounced /ɸ/ (or a Greek letter phi) by the Japanese, i.e., a voiceless bilabial fricative, but in English it's an different sound altogether /f/ made with the upper lip on top of the lower row of front teeth. Same with Spanish intervocalic {b} and {v}; they are both pronounced as voiced bilabial fricatives, and constantly sound like an English /v/ or /b/.
Hope that helps.
