The beginning of the Igeres HaRamban says:
תִּתְנַהֵג תָּמִיד לְדַבֵּר כָּל דְּבָרֶיךָ בְּנַחַת, לְכָל אָדָם וּבְכָל עֵת, וּבַזֶּה תִּנָּצֵל מִן הַכַּעַס, שֶׁהִיא מִדָּה רָעָה לְהַחְטִיא בְּנֵי אָדָם. וְכֵן אָמְרוּ רַבּוֹתֵינוּ ז"ל (נדרים כב ע"א): כָּל הַכּוֹעֵס – כָּל מִינֵי גֵיהִנּוֹם שׁוֹלְטִים בּוֹ, שֶׁנֶּאֱמַר (קהלת יא י): "וְהָסֵר כַּעַס מִלִּבֶּךָ, וְהַעֲבֵר רָעָה מִבְּשָׂרֶךָ". וְאֵין "רָעָה" אֶלָּא גֵיהִנּוֹם, שֶׁנֶּאֱמַר (משלי טז ד): "וְגַם רָשָׁע לְיוֹם רָעָה".
Accustom yourself to always speak all of your words calmly, to every man and at every time. In doing so you will prevent your anger from flaring, which is a bad attribute in a man which may cause him to sin. And accordingly said our Rabbis, may their memories be a blessing: (Nedarim 22a) "Anyone who gets angry - all of Gehinnom holds sway over him, as it says: (Kohelet 11:10) 'And remove the anger from your heart, and take away the bad from your flesh', and 'bad' can only mean Gehinnom, as it says (Proverbs 16:4): 'And the sinner, he too, will have his day of bad'."
(Translation from Sefaria)
My question is: What does the Ramban mean when he uses the word בנחת? Does that mean you should never raise your voice? If so, should you not yell even while learning with a chavrusa?