What language construct does the "Box scope" in jetpack compose correspond to?

I'm new to android's jetpack compose as well as to kotlin, and I'm having a hard time figuring out how some stuff work, here I'm particularly interested in things like

Box {
    somecomposablefunc()
}

or

Row {
    somecomposablefunc()
}

Are these composable functions with no arguments, and so the whole argument list with parentheses can be omitted (as a feature of kotlin), or are they some android invention, or something else? Sorry if I'm asking for help about well documented stuff, but I get headache from navigating both android's and kotlin's docs.