Strange, the translation given for "segura" in this sentence is "hold". So non-native speakers would be confused as to what "The kitchen does not hold" could actually mean in Portuguese.
As an adjective "seguro/segura" means "safe".
As a verb, "ele segura (segurar)" means "he holds".
Notice the verb "é" in the sentence. The kitchen IS (adjective).
The dictionary gives one meaning of "seguro/a" as "safe". The translation on hover is for the verb "segurar", but here the adjective is used.
it means "the kitchen is not safe", as in "there might be a serial killer in there".
As a follow-up to TheChexMixer's question, how would you say "the kitchen is not secure", meaning that you can't prevent outsiders from going and stealing, for example?
Exactly the same way. As far as I know there's no a distinction between "safe" and "secure" in Portuguese.
Refering to Coayuco's question (and your response), I feel that one could infer from the statement that the kitchen (not being secure) means that it is not locked, no?
It can, yes. For example, as in "I'm not sure we're in Kansas anymore" - "Eu não estou seguro/a de que ainda estejamos no Kansas"