Hi @Samiaa,
Many thanks for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
It looks like the silicone around your basin and tap hole has worn out and needs to be replaced.
I would suggest removing the old silicone using a utility knife to cut it free from the surface beneath. Make sure you wear the relevant personal protective equipment and take all necessary precautions while working with knives. Specifically, gloves, a long sleeve work shirt and eye protection.
Once the old silicone is removed, clean the area thoroughly using a Mr Clean Handheld Iron Scrub Brush and CLR Calcium Lime Rust Remover.
Once cleaned, grab a tube of SikaSeal Kitchen And Bathroom Silicone Sealant, a caulking gun and some silicone scrapers.
Apply a bead of silicone around the sink and tap hole, ensuring the bead is large enough to completely cover the gap. Once the bead is in place, strike off the excess using the silicone scrapers to create a clean finish.
Caulking is a reasonably simple task, but it is always important to have a bucket of water and plenty of paper towels handy for clean-up, as it can be quite messy.
You might like to have a look at How To Silicone a Gap for some further guidance.
Let me know if there's anything else I can assist with.
Jacob
