It looks to be a classic wool pea coat in either black or navy blue (appears to be black in the photos). If it's just a generic pea coat with the signature anchor buttons (which it looks to have based on the button near the collar
in this photo) inspired by the one Navy sailors wear, the good news is those are pretty easy to find. Army Navy stores,
Old Navy, Gap, etc. You can probably even find on on sale at this point as we head into the summer months.
Now, if on the other hand it's a designer pea coat inspired by that style, we'll have to see some more telling details to know what we're looking for. Which it very well could be considering that a pea coat is one of the most iconic outerwear styles of all time.
Right now though, my money is on classic pea coat. Most designer versions don't use the anchor buttons.