6 A jar made of alabaster stone was normally used for very precious substances like perfumes. It normally had a long neck which was sealed and had to be broken off so the contents could be used.
7 Μύρον (muron) was usually made of myrrh (from which the English word is derived) but here it is used in the sense of ointment or perfumed oil (L&N 6.205). Nard or spikenard is a fragrant oil from the root and spike of the nard plant of northern India. This perfumed oil, if made of something like nard, would have been extremely expensive, costing up to a year’s pay for an average laborer.
8 Grk “as he was reclining at table.” 1st century middle eastern meals were not eaten while sitting at a table, but while reclining on one’s side on the floor with the head closest to the low table and the feet farthest away.

In other versions

a woman came up to him with an alabaster flask of very expensive ointment, and she poured it on his head as he reclined at table.

a woman came to him with an alabaster jar of very expensive perfume, which she poured on his head as he was reclining at the table.

a woman approached him with an alabaster jar of very expensive perfume. She poured it on his head as he was reclining at the table.

While he was eating, a woman came in with a beautiful alabaster jar of expensive perfume and poured it over his head.

a woman came up to him holding an alabaster flask of very expensive perfumed oil, and poured it out on his head while he was reclining at table.

There came unto him a woman having an alabaster box of very precious ointment, and poured it on his head, as he sat at meat.

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