He emphasized his words to the judge before his opponent appeared
He articulated or explained his arguments before the judge while the opposing litigant had not yet arrived. This is considered forbidden because the judge is susceptible to being persuaded by the arguments and liable to form in his heart a bias toward one side, thus losing objectivity.
(See above: Sotah 21b).
Translation
Expression (Hebrew)
הִטְעִים דְּבָרָיו לַדַּיָּן קֹדֶם שֶׁיָּבֹא בַּעַל דִּין חֲבֵרוֹ
Definition (Hebrew)
הִשְׁמִיעַ אוֹ נִמֵּק אֶת טַעֲנוֹתָיו בִּפְנֵי הַשּׁוֹפֵט כְּשֶׁעֲדַיִן לֹא נָכַח בַּעַל הַדִּין הַשֵּׁנִי בַּמָּקוֹם. הַדָּבָר נֶחֱשָׁב לֶאֱסֹר כִּי הַשּׁוֹפֵט עָלוּל לְהִשְׁתַּכְנֵעַ מֵהַטְּעָנוֹת וַעֲלוּלָה לְהִקָּבַע בְּלִבּוֹ נְטִיָּה לְצַד אֶחָד וִיאַבֵּד אֶת הָאוֹבְּיֶקְטִיבִית.
(רְאֵה לְעֵיל: סוֹטָה כא ע"ב).