This is the 3626th most frequent Portuguese word.
seguras
"Seguras" means "safe" or "secure" (feminine plural form).
Here, 'seguras' is the plural feminine form of the adjective 'seguro', meaning 'safe', and it agrees with the noun 'pontes' (bridges), which is feminine and plural.
As pontes são seguras.
The bridges are safe.
In this case, 'seguras' is part of the phrase 'Elas seguras', where 'seguras' functions as a verb (from 'segurar', meaning 'to hold') conjugated in the past participle.
Elas seguras a corda firmemente.
They hold the rope firmly.
Here, 'seguras' is an adjective describing 'gestões' (management), indicating safety or reliability.