That’s weber latex - bonding agent and multipurpose additive for mortar improvement
what it's used for:
this is a liquid additive you mix into cement, mortar, and plaster to make them stronger and more waterproof. it’s made by saint-gobain weber.
main uses:
1. bonding agent - creates a strong "glue" layer between old concrete and new plaster/tile adhesive
2. makes mortar more flexible - reduces cracks in render, screeds, and plaster
3. increases water resistance - makes plaster and concrete less permeable to water
4. improves adhesion - helps tiles, renders, and screeds stick better to surfaces
5. algae resistant - good for external walls to resist algae/mold growth