what / that thing (used in place of words you can't remember at the moment.)

what

what is this?

the first sight of something / something seen for the first time

one should start a big project with immediate, practical steps; start small / the person who proposes something should be the first one to take practical steps to implement it

let's see; what have we got here

which (of three or more) / which one /

Nothing

what

Doing a number of traditional things that commemorate a new year. / (by extension, informal) Having sex for the first time in a new year.