According to your previous post, you are going to make a transaction from a legacy address to a native segwit address.
If that's the case, your transaction (virtual) size will be around 190 vbytes and you will pay around 190 vbytes * fee rate (in sat/vbyte) as fee.
For example, if you set the fee rate to 2 sat/vbyte, you will pay around 380 sat as transaction fee.
To know how much fee rate you need to use for your transaction, you can visit
mempool.space and you can also use electrum's own fee estimations. Both work well.
I've been meditating on that and I think I'm starting to understand, so on the mempool main page the green example blocks showing the sat, btc amount, and approx transaction time... Then below that is shows transaction fees (no priority, low priority, medium priority, high priority) with the sat v/B under it, but I don't understand the dollar amount they show with it and how it relates to my specific situation (i.e. right now it shows medium priority 4 sat/vB is $0.58).
For example, using your example above, if it was 4 sat/vB and I paid 760 sat as a transaction fee, how much would be deducted from 0.3 BTC?