How 5050 rgb led strip color to be white?

Yes, an RGB strip can produce white. You just have to mix Red, Green and Blue values to produce a white color.

5m/roll / SMD5050 / 60pcs/m / 10mm PCB / 11.5W/m / DC12V & DC24V with CE ROHS UL

The RGBW strip already includes a separate white LED element so that you do not have to sacrifice your RGB into producing white. The white in RGBW is a pure white from a white LED, this makes it easier to achieve custom or unique colors that cannot be achieved by using an ordinary RGB.

5m  /  SMD5050  /  60pcs/m  /  10mm PCB  / max 18W/m  /  DC12V /  RGBW, Single Chip

5m / SMD5050 / 60pcs/m / 10mm PCB / max 11.5W/m / DC12V/ RGBW, 30pcs RGB & 30PCS white leds

In short RGB simulates a white color, but if you want a more pure white color you will need an either an RGBW, Warm White, Nuetral White, or Cold White strip.