How should the core and thread counts of Core i5 14400F be understood, and do more cores help in games?

  10 cores and 16 threads (6 P-cores + 4 E-cores), and the F suffix means no integrated graphics — you need a discrete GPU to get a picture.

  That's plenty for mainstream gaming and everyday development. Compiling, encoding, and rendering can use the extra threads, but sustained all-core performance is capped by power limits and cooling. And on 13th/14th gen, update the BIOS microcode — Intel fixed a stability issue that affected these.