This is a lamp from LEDVANCE which requires one bulb. This fluorescent fixture should be used indoors and recommended wattage for bulbs is maximum 16W.
From Amazon
Linear luminaire LED: for ceiling/wall, SubMARINE© Integrated Slim Value / 24 W, 220…240 V, beam angle: 120°, Cool White, 4000 K, body material: polycarbonate (pc), IP65, 1-pack
Conrad Electronic
LEDVANCE SUBMARINE (EU) Wet room diffusor LED (monochrome) G13 16 W Neutral white Grey