Exegesis:
ekeinos de ho doulos ‘but that servant…,’ referring forward to ho gnous, etc., and to be distinguished from the one to whom vv. 43, 45f refer.
ho gnous to thelēma tou kuriou autou ‘who did know what his master wants.’
thelēma ‘will,’ i.e. what is willed, here of that which one wants to be brought about by somebody else.
kai mē hetoimasas ē poiēsas pros to thelēma autou ‘and who has not made preparations or acted according to what he wants.’ autou refers to tou kuriou. For pros. For hetoimazō cf. on 1.17.
darēsetai pollas (scil. plēgas) ‘will be beaten with many (strokes),’ hence ‘severely’ (cf. New English Bible).
derō ‘to beat,’ here with accusative of content.
(V. 48a) ho de mē gnous ‘but he who did not know,’ i.e. ‘what his master wants,’ with to thelēma tou kuriou autou understood from v. 47.
poiēsas de axia plēgōn ‘but who did what deserves strokes,’ i.e. what deserves punishment. plēgē, cf. on 10.30.
darēsetai oligas (scil. plēgas) ‘will be beaten with few (strokes),’ hence ‘lightly.’
Translation:
Again a change in the sentence structure may be preferable, e.g. ‘if a servant knows…, he will receive….’
Did not make ready or act according to his will. Where the verbs to be used are obligatorily transitive one may say, ‘did not make ready or do what he (i.e. his master) wanted him to do.’
Shall receive a severe beating. Such constructions with ‘receive’ can often be rendered as passives, e.g. ‘will be beaten severely,’ then, with a further shift, ‘his master will beat him severely.’ For indirect agency cf. the remark on v. 46. Beating here probably refers to beating with a stick or whip.
(V. 48a) He, referring to another hypothetical servant.
Did what deserved a beating, or, ‘did what is repaid/punished with blows’ (cf. Yao), ‘did something that properly brings (lit. causes-to-come) blows’ (Bahasa Indonesia RC); or introducing a reference to the person to be beaten, ‘did things for which he deserved a beating, or, ought to be beaten,’ ‘acted so that his master must beat him,’ etc., see above.