What is the meaning of "...the cost of a 5 year R01..."? I assume this is something  related to the US and  NIH Research Project Grant Program (R01), but I don't understand how one put value on a "single  word"
Is there anyone who understands this sentence and care to elaborate what was implied by that?
According to the yearly NIH report, in 2018, a total of 625 NIH Research Project grants (R01) were awarded, and the total cost for NIH (funding + other costs) of these grants was $347,466,328. This averages to $347,466,328/625, or about $556,000 of funding per year in one grant, or $2,780,000 in total for a 5-year grant

The Specific Aims application document is considered to be (one of) the most important part(s) of the application. The example document on that website has 601 words. The tweet in your question exaggerates the importance of the Specific Aims document, and implies that the document is "worth" the whole $2,780,000 of the grant. The cost of each word would then be $2,780,000/600, or approximately $4633 per word.