Exegesis:

ho de Iēsous akousas apekrithē autō ‘but when Jesus heard (this) he said to him,’ cf. on 1.60. The object of akousas which is not stated, are the words spoken by the man from Jairus’ house. autō refers to Jairus.

monon pisteuson ‘only believe.’ The aorist tense of the imperative suggests the punctiliar nature of the injunction, ‘have faith (or, believe) right now (or, at this very moment),’ now that the sad message that she is dead has come. monon.

kai sōthēsetai ‘and she will be well’; subject is the daughter.

Translation:

Answered him. The pronoun refers to Jairus, not to the messenger; hence preferably, ‘said to Jairus, or, to the ruler’ (cf. The Four Gospels – a New Translation, Balinese), ‘interposed a word towards Jairus’ (Javanese, and cf. New English Bible); see also on 3.16.

Only believe, or, ‘do nothing except believe,’ ‘have faith, nothing else.’ For only cf. on 4.8; for the verb see the references on “faith” in 5.20.

She shall be well. The Greek verb does not contrast here with demon possession (v. 36) or illness (v. 48), but with death, which may make necessary another rendering, e.g. ‘she shall live (again)’ (Batak Toba), ‘she shall have her spirit of life returned to her,’ or, ‘she shall be snatched (back to life)’ (two alternatives in Cuyono). A more generic expression is also used, e.g. ‘it will again return good yet that (i.e. it is going to be all right)’ (Tboli).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.