This is the 10144th most frequent Turkish word.
başkanlardan
"From/among the presidents/chairpersons."
Here, 'başkanlardan' is used to indicate one member from the set of all chairpersons.
Başkanlardan biri toplantıya geç kaldı.
One of the chairpersons arrived late to the meeting.
In this sentence, 'başkanlardan' specifies a subset of chairpersons that is in favor of the regulations.
Başkanlardan bazıları yeni kuralları destekliyor.
Some of the chairpersons support the new regulations.
Here, 'başkanlardan' is used to contrast one chairperson with the rest.