I just bought this Panasonic S5II because everyone said the autofocus was finally good but now I'm just staring at the hole in the front of the camera and I feel so stupid. I spent almost all my savings on the body - about $2000 - and I completely blanked on the fact that I actually need glass to make it work. I've been looking at the lens options online and there are just way too many numbers and I'm honestly getting a massive headache. F4? F2.8? Does it really matter that much?

I just want to take pictures of my kids playing and some nice landscape shots when we go to the Grand Canyon next month. I dont want to carry five different lenses because I know I'll just lose them or get dust inside the camera which sounds like a total nightmare. So I was thinking maybe that 20-60mm one that comes in the kit? But then I saw people saying it isn't fast enough and I have no idea what that even means. Like is it slow at taking the picture?

My budget is pretty tight now, maybe $800 max since the camera was so much. I saw a Sigma 24-70 thing but its huge and looks like a literal brick and I dont want to break my neck carrying it around all day. My logic was that a zoom is better so I dont have to keep swapping things out but I'm just so lost with all these brands. What is the one lens I should get that just works for everything?...