This is the 13359th most frequent Russian word.
наблюдательного
"Observant" or "watchful."
In this sentence, 'наблюдательного' is used as an adjective describing the character trait of being observant.
Он был известен как наблюдательный и внимательный учёный.
He was known as an observant and attentive scientist.
Here, 'наблюдательного' forms part of a technical term 'наблюдательного пункта', referring to an observation point, emphasizing the context of observation.
В условиях наблюдательного пункта было важно сохранять концентрацию.
Under the conditions of the observation post, it was important to maintain focus.
In this case, 'наблюдательное' describes the approach or attitude towards being attentive to details as an attribute.