practical person; doer; man of action
Refers to someone who puts ideas into practice, as opposed to a theorist. Often used in contrast with 理論家.
He is a doer, not a theorist.
We are looking for someone with extensive experience as a practitioner.
実践者 is a more general term for a practitioner; 実践家 often implies a more established or dedicated doer.
Compound of 実践 (practice, implementation) and 家 (person, specialist).