Two resistors in one SOT-883 package
The BCR 103L3 E6327: This is an NPN pre-biased transistor — a switching transistor with two 2.2 kOhm resistors (R1 on the base, R2 across the emitter-base) built into the same SOT-883 package. That means the bias network is already trimmed and matched; you drop it onto the board, connect the collector load and the drive signal, and the transistor turns on and off at the right operating point without external resistors. Rated for 50 V collector-emitter breakdown and 100 mA continuous collector current, with a maximum power dissipation of 250 mW. The 140 MHz transition frequency tells you it handles low-speed switching and logic-level interfacing comfortably — think relay drivers, LED indicators, or level-shifting a 3.3 V logic output to a 5 V load.
What the saturation and gain numbers mean for your circuit
Vce(sat) is specified at 300 mV maximum with a 1 mA base current driving 20 mA collector current. That is a forced beta of 20 — the same ratio used for the minimum DC current gain spec (hFE of 20 at 20 mA, 5 V). So when you design the base drive, budget for a beta of 20 in saturation; the transistor will pull the collector down to under 300 mV, which is well within the Vce(sat) ceiling for driving a relay coil or an LED string at 20 mA. The collector cutoff current is 100 nA maximum (ICBO) — negligible leakage for most low-power loads, but worth noting if the output drives a high-impedance CMOS input that could float. At 50 V Vce and 85 °C ambient, leakage multiplies; the 100 nA spec is at 25 °C, so derate upward if the board sits in a warm enclosure.