A khabar maqbūl (خبرِ مقبول) is a report whose narrators are reliable and trustworthy. Here, khabar (خبر) means a Hadith report.
Thiqah (ثقہ) means a narrator who can be trusted in transmitting reports. Merely knowing someone does not establish this reliability.
The required qualities1 must be present. A full investigation also considers other conditions concerning the chain and the reported text.
1. Required qualities: the necessary qualities a narrator must possess for acceptance. Their details will be studied separately.