Source https://www.etz-hayim.com/hebrew/pages/aleph-bet3.php
Source

The Letters of the Hebrew Alphabet

Lesson 3.

Hebrew letters with different written forms …The Sofit letters

While the Hebrew aleph-bet consists of 22 letters, all of which are consonants, some of these letters are written differently when they occur at the end of a word. These different forms for the letters are known as sofit letters. There are FIVE Hebrew letters which have are sofit form. They are kaf/, mem/, nun/, pey/ and tsade/.

The word sofit/means “final” or “end.”

Sofit letters

Although the written form of these consonants changes when they appear at the end of a word the pronunciation is the same. As a general rule the kaf sofit/ is pronounced as a khaf and pey sofit/ as fey when they appear as a final letter in a word.

The softer fricative pronunciation takes precedence because the final consonant usually follows a vowel.

The chart shows the five consonants that are written differently when they occur at the end of a word and take the sofit form.

Lesson 4. Sound alike letters. HERE…
Some consonants sound similar…