We start with a short introduction to turbulence of fluids and we look at it as a stochastic phenomenon. In the first part of the present lecture notes, we focus on the one-point statistical description of single-phase turbulent flows. We recall and concisely present the Probability Density Function method, implemented in terms of the Lagrangian stochastic approach for the modelling of free-shear and wall-bounded turbulence. In the second part of the chapter, we present selected examples of the so-called multiphysics turbulent flows. The topics of the overview include the dynamics of passive admixtures, in particular stochastic modelling of micromixing processes (briefly mentioning also chemically reacting flows), and the two-phase flows with inertial particles. For the latter, mainly the subfilter dispersion modelling is discussed in the context of large-eddy simulation.