The date is too eroded to be read securely, though 1/2/3- AJAW seems probable for the tzolkin position, 1/2/3 for the month coefficient, and probably either Muwan or Xul for the month name.
Based on carving style and its association with others in Structure 20, this heavily eroded lintel seems to depict the arraignment of four captives before Bird Jaguar IV and one of his lieutenants. This is also supported by the fragmentary chuhkaj "capture" glyph appearing at B2.
TRANSCRIPTION, TRANSLITERATION AND TRANSLATION
Other than the fragmentary date (B1-C1, discussed above) and the "capture" glyph (B2), this text is far too eroded to be read.