Interlaced and non-interlaced are terms describing how a single frame (or picture) of television is put on the screen. In both cases the frame is composed of a number of horizontal lines which together make up a page. The "obvious " way to do this is to paint the lines in order : 1, 2, 3, 4, . . . .623, 624, 625. Unfortunately this leads to a visible flicker effect on the screen.
A way to reduce the flicker effect is to paint the screen in two parts : 1, 3, 5, . . . 621, 623, 625, 2, 4, 6, . . . 620, 622, 624. The result of this is to interlace two halves of the image. It's not really a brand new technical term - people have been interlacing the fingers of their hands and using the word to describe it for hundreds of years.
Some TV systems, especially low cost security systems, use the "obvious" method. This is called non-interlaced.