Hi @jassy,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
The seams between the floor and wall around the perimeter of a shower are usually sealed with a silicone sealant such as this Selleys White Wet Area Waterproof Silicone Sealant.
I'd suggest you start by giving the seam a good clean with some soapy water and a small brush like a toothbrush or Grout Brush.
Once dry, you can apply the silicone sealant to the seam. Check out How To Apply Bathroom Sealant and How To Silicone a Gap for some guidance on the process.
If you have any further questions, please let me know so I can assist further.
Jacob
