Help with Makefile

I programmed not so long ago and I am familiar with the simplest Makefiles and the make utility, but I don’t understand anything and there’s no time at all to explain these lines, thank you very much!:

bin/test_button: src/test_button.c lib/ev3c.a //я понимаю что эти 2 файла //зависимости mkdir -p $(@D)// вот что означает -P $(@D) ?? $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude // вот эту строку вообще я не понял. 

This is what was declared at the beginning of this file:

 CFLAGS += -O3 ifndef RANLIB RANLIB = ranlib endif 

Here is the file with which you do not need to understand:

 CFLAGS += -O3 ifndef RANLIB RANLIB = ranlib endif all: lib/ev3c.a bin/test_sensor bin/test_motor bin/test_lcd bin/test_button bin/test_led bin/test_battery obj/%.o: src/%.c include/%.h include/ev3c.h Makefile mkdir -p $(@D) $(CC) -c -o $@ $< $(CFLAGS) -Iinclude lib/ev3c.a: obj/ev3c_core.o obj/ev3c_lcd.o obj/ev3c_sensor.o obj/ev3c_motor.o obj/ev3c_button.o obj/ev3c_led.o obj/ev3c_battery.o mkdir -p $(@D) $(AR) rc $@ $^ && $(RANLIB) $@ bin/test_sensor: src/test_sensor.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude bin/test_motor: src/test_motor.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude bin/test_lcd: src/test_lcd.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude bin/test_button: src/test_button.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude bin/test_led: src/test_led.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude bin/test_battery: src/test_battery.c lib/ev3c.a mkdir -p $(@D) $(CC) -o $@ $< lib/ev3c.a $(CFLAGS) -Iinclude documentation: include/*.h mkdir -p /tmp/ev3DocumentationTemp naturaldocs -i . -xi ./ev3c_documentation -o HTML ev3c_documentation -p /tmp/ev3DocumentationTemp .PHONY: all clean clean: rm -rf obj lib bin rm -f *~