to have a similar level. The two horses were neck and neck at the finish fine. They are neck and neck at English

It means that the horses/people were very near each other, close to the finish line and either of them could win the race.

It's a horse racing analogy. Horses which are racing but neither one is overtaking the other are described as "neck-and-neck." A horse can win by a nose, a neck, or a length (literally).

neck and neck means get together