What's wrong with this website

I'm in the process of "learning" again (after many years of not coding) .........

I recently got an unexpected promotion (more like change of role actually) that will allow me to code again. My boss mentioned about getting someone with more experience than me to help me get started, but I'll be tackling projects mostly on my own eventually after a while. Please point me to the right direction:

http://string99.xyz/

TIA!!

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