As indicated in the code, it is performing a
wildcard Find, for which see:
Finding and replacing characters using wildcards
In [!^13]{1,}, the:
• [] pair says to find any instance of whatever is defined between them
• ! says to NOT find what follows
• ^13 represents ASCII 13, which is the first character of the ASCII 13 & 11 pair that together create a paragraph break
• {1,} says to continue finding such characters for as long as they go.
Hence:
.Text = "Organization:[!^13]{1,}"
tells Word to find 'Organization:' followed by any series of characters that do not include a paragraph break.