Examples are [kʷ, ɡʷ, xʷ, ɣʷ, ŋʷ], which are pronounced like a [k, ɡ, x, ɣ, ŋ], with rounded lips, such as the labialized voiceless velar plosive [kʷ] and labialized voiced velar plosive [ɡʷ], obstruents being common among the sounds that undergo labialization.
An example of this is the development of Proto-Indo-European *kʷ, *gʷ before *a or *o into Greek /p, b/, producing cognates as different as English come and basis.
A notable development is the initial *kʷ in Proto-Indo-European interrogative words.
In English, it developed into wh or h (how), pronounced /w/ in most dialects and /h/, respectively, via Grimm's law followed by wh-cluster reductions.
The English phonemic spelling kw for qu (as in kwik) echoes its origin.