Meaning of Lag ba'Omer:
Lag - 33
Ba - in/of
'Omer
(טו) וּסְפַרְתֶּ֤ם לָכֶם֙ מִמָּחֳרַ֣ת הַשַּׁבָּ֔ת מִיּוֹם֙ הֲבִ֣יאֲכֶ֔ם אֶת־עֹ֖מֶר הַתְּנוּפָ֑ה שֶׁ֥בַע שַׁבָּת֖וֹת תְּמִימֹ֥ת תִּהְיֶֽינָה׃ (טז) עַ֣ד מִֽמָּחֳרַ֤ת הַשַּׁבָּת֙ הַשְּׁבִיעִ֔ת תִּסְפְּר֖וּ חֲמִשִּׁ֣ים י֑וֹם וְהִקְרַבְתֶּ֛ם מִנְחָ֥ה חֲדָשָׁ֖ה לַיהוָֽה׃
(15) And from the day that you bring the sheaf ('omer) of elevation/waving offering—the day after the Shabbat—you shall count off seven whole weeks. (16) You must count until the day after the seventh week—fifty days. Then you shall bring an offering of new grain to Adonai.
In the Torah, the Omer is a period of seven weeks that we count from Passover to Shavu'ot (Leviticus 23:15-16).
In the Talmud, we learn about something else that happened during the 'Omer:
שנים עשר אלף זוגים תלמידים היו לו לרבי עקיבא מגבת עד אנטיפרס וכולן מתו בפרק אחד מפני שלא נהגו כבוד זה לזה. והיה העולם שמם עד שבא רבי עקיבא אצל רבותינו שבדרום ושנה להם: רבי מאיר ורבי יהודה ורבי יוסי ורבי שמעון ורבי אלעזר בן שמוע והם הם העמידו תורה אותה שעה. תנא כולם מתו מפסח ועד עצרת. אמר רב חמא בר אבא...: כולם מתו מיתה רעה. מאי היא? אמר רב נחמן: אסכרה.
Rabbi Akiva had twelve thousand pairs of students in an area of land that stretched from Gevat to Antipatris in Judea, and they all died in one period of time, because they did not treat each other with respect. And the world was desolate of Torah until Rabbi Akiva came to our Rabbis in the South and taught his Torah to them. This second group of disciples consisted of Rabbi Meir, Rabbi Yehuda, Rabbi Yosei, Rabbi Shimon, and Rabbi Elazar ben Shamua. And these are the very ones who upheld the study of Torah at that time...With regard to the twelve thousand pairs of Rabbi Akiva’s students, the Gemara adds: It is taught that all of them died in the period from Passover until Shavu'ot. Rav Ḥama bar Abba said...: They all died a bad death. The Gemara inquires: What is it that is called a bad death? Rav Naḥman said: Diphtheria (a disease also called whooping cough).
Story that during this counting period all of Rabbi Akiva's tens of thousands of students died - no more Torah in the south of the land of Israel. He had to start all over again with a last few students.
During Rabbi Akiva's life, there was a big war between the Jewish people and Rome (the third and last one), against oppression and colonization. Rabbi Akiva encouraged Jews to fight.
We lasted a long time, but many many people died, and in the end all the Jewish towns and cities in the south of Israel were destroyed. Over half a million Jews were killed. Many others were sold into slavery. The Romans also killed a lot of rabbis, including Rabbi Akiva. Today, many people think that that is what the story in the Talmud is really about.
So why should we be so happy on Lag ba'Omer?
According to the 13th century scholar, Menahem Me'iri, the day that Rabbi Akiva's students stopped dying was the 33rd day of the Omer, Lag Ba'Omer.
Could have been a day that we won a battle, one small part of the war
Hope in the face of darkness
Celebrate the second set of students he left behind who passed on Torah
Celebrate the survival of Judaism and the Jewish people
Our freedom in the US and the existence of the State of Israel
As Jews, we take even the darkest moment and find a source of hope in it