After something happens, you have a much better understanding in hindsight of what would have been appropriate to do in such a situation, and this understanding itself is called “hindsight”, pronounced /ˈhaɪndsaɪt/ (haaynd-saayt). The “hind” is etymologically related to “behind”, and so is the pronunciation.
On the other hand, “hinder” is also etymologically related to “behind”, but is pronounced /ˈhɪndə/ (hin-də) in the UK resp. /ˈhɪndɚ/ (hin-dr) in the US. The same applies to “hindrance” /ˈhɪndrəns/ (hin-drəns).