The primary themes of Parshas Behar are Shemitah and Yovel - the Sabbatical and Jubilee years. At first glance, it would appear that these topics are presented at this juncture in Sefer Vayikra as a continuation in the spectrum of differing types of kedushah. Parshas Kedoshim dealt with personal kedushah, Parshas Emor addressed legal and objective kedushah status of persons (Kohanim) and times (Yom Tov), and Parshas Behar now turns to Kedushas Ha'Aretz - holiness associated with the Land of Israel.
The parshah can be understood more deeply through analysis of one aspect of Yovel. The Torah commands (25:9) that the shofar be sounded on Yom Kippur of the Yovel year. In fact, Rashi posits (ibid. v. 10) that the very name "Yovel" is derived from the shofar blowing which marks the fiftieth year. What does the shofar have to do with Yovel? Why is the shofar of Yovel blown on Yom Kippur during that special year?
Yom Kippur is all about teshuvah - return. On Yom Kippur, we seek to reconnect and reestablish our relationship with Hashem and renew ourselves with a state of purity. Yom Kippur is the day when we become spiritually realigned. It is the apex of teshuvah.
Yovel is quite similar to Yom Kippur, for Yovel also has a theme of teshuvah, of return. Unlike Shemitah, Yovel calls for return of ancestral property and for permanent freedom for the Eved Ivri (Hebrew servant). The land is reassociated with its original proprietors, and man who served man is now reconnected directly to Hashem's avodah (service).
Thus, the shofar of Yovel is sounded as a call to herald return. Yom Kippur of Yovel marks the complete spiritual and physical return of B'nei Yisroel to a primordial, pristine state. (See Ramban on Vayikra 25:10.) The special confluence of Yom Kippur and Yovel is marked by the shofar blasts of this grand state of return.
Whereas Yovel reflects teshuvah, akin to Yom Kippur, Shemitah represents an awareness of Hashem's authority over all. Similar to Shabbos, Shemitah is primarily marked by a cessation from work, thereby proclaiming that the land and its produce are the property of Hashem. Shemitah's Cancellation of Loans (Hashmatas Kesafim) is also indicative of Hashem's ultimate authority over all that is "ours". The Torah refers to Shemitah as "Shabbos", underscoring the commonality of Shabbos and Shemitah, for both are modes of expression of Hashem's mastery over all.
Yovel is the pinnacle of the Shemitah cycles. Indeed, agricultural work is prohibited during Yovel as well. This is because inherent within return to Hashem and the primordial state which He ordained is a recognition of His ultimate control and ability to define the universe. On Yovel, we take the message of Hashem's mastery as expressed by Shemitah one step further and restore all to its original state, such that Hashem's kingship is not just recognized, but is vividly and animatedly demonstrated as well, as we restore the world according to the Divine Will.