It is likely a film capacitor. They are much larger for a given value, but they have very good characteristics (tolerance, linearity, dielectric absorption, usually handle lots of voltage, etc).
The third digit gives you the multiplier in picofarads. So a 334 is 33 with 4 zeros or 330000 pf. Now just convert to your favorite farad. For example to go from pico 330000pf x (1uf/1 x 10^6pf) = .33 since the pf's cancel in the equation, your left with uf, hence .33uF.
Of course, after using these parts for awhile, you won't need any math. It will just come to you
The K means 10% tolerance, which means that the actual capacitance is within 10% of 0.33μF. Take a look at this chart by Dean Huster.
B = ±0.1pF
C = ±0.25pF
D = ±0.5pF
E = ±0.25%
F = ±1.0%
G = ±2%
H = ±2.5%
J = ±5% *
K = ±10% *
L = ±15%
M = ±20% *
N = ±30%
P = -0, +100%
S = -20, +50%
W = -0, +200%
X = -20, +40%
Z = -20, +80% *