This appears to be describing instructions on how to write a particular kind of Kameya/Amulet (קמיע). This often involves making a special kind of ink that is often derived from a particular plant which is prepared in a specific manner.
In this case, the Hebrew saraph (שָׂרָף) is saying that the plant needs to been charred (like how char cloth is made, a slow oxidation which produces a very dark black residue which is the color base for the ink or dye).
The plant itself appears to be some part of the Afarsimon tree which grew native around the Dead Sea. Afarsimon was a unique and highly prized species of Persimon specific to Israel. It's oil was also used in the Anointing Oil. Sadly, the Romans uprooted virtually all of the native Afarsimon trees from Israel in an effort to transplant to species to Italy at the time of the destruction of the second Temple. This is one of the things that is supposed to be returned to us during the days of Moshiach.
This is indicated from the parallel usage found in Yechezkel 27:17 which refers to Pannag (a term used in Sefer Yosifun for Afarsimon) as Koolya.
יְהוּדָה֙ וְאֶ֣רֶץ יִשְׂרָאֵ֔ל הֵ֖מָּה רֹכְלָ֑יִךְ בְּחִטֵּ֣י מִ֠נִּית וּפַנַּ֨ג וּדְבַ֤שׁ וָשֶׁ֙מֶן֙ וָצֹ֔רִי נָתְנ֖וּ מַעֲרָבֵֽךְ׃
The Targum Yonatan to this posuk:
יְהוּדָה וְאַרְעָא דְיִשְׂרָאֵל אִינוּן תַּגָרֵיךְ בְּהִטֵי רִיחוּשׁ וְקוֹלְיָא וּדְבַשׁ וּמְשַׁח וּשְׁעֵיף יְהָבוּ בַּחֲנּוּתָיִךְ:
The root of the word is קלי or קלה as found on page 1375 of volume 2 in Jastrow and in the second definition means: to consume, burn, roast or parch.
A related answer: https://judaism.stackexchange.com/a/76344/7303
