Although you've posted this in a Fiesta forum, the answer relies on getting it to a mechanic that is familiar with the manual transmission and especially Ford and the IB5 (5-speed) and B6 (6-speed) for their shifter assembly and the linkage to make it work is oftentimes exposed to the elements that can cause binding and hard shifting.
It sounds like - by your description using the term "Grind" means the shifter forks are damaged, between 1st and 2nd gear on a 5-speed transmission is the Reverse gear - which in itself would work to back the vehicle up, it is sandwiched between the two gears and their respective synchronizers. Which, those synchronizers are what the gears use to "align themselves" to the input shaft and to the output shaft - then when you release the clutch the transmission will engage; as that gear you selected, and work accordingly to that gear.
When you encounter grind, and the hard shifting caused by it, remember that the shifter forks that move one gear on, and pull the other one off - also work (push or pull) the synchronize mechanism as well. If it's not done right due to either the binding of the synchronizer or the gear is too badly worn - you encounter this noise. IN a normal transmission shifting - it's done as if you were the conductor of a symphony, the section affected by your shifting does what you're requesting - in unison to the beat. IF the synchronizers are not working or damaged, they can't follow the beat so they cause the clash and grind you hear.
So it may mean the transmission needs service or replacement - consider the mileage and the number of years it's been used. Being a 2015 and mileage and it';s age - it's easier to replace the whole assembly - including the transaxle - than to try and rebuild the transmission itself for the year of your vehicle and if it's over 50,000 miles and you've had this problem for several months - for both the transmission and it's differential transaxle - use the same housing and fluids - so the battered teeth and the metal filings and shards also are wearing down the drive surfaces making the matter worse over time and use.
