The pioneering measurements of galvanomagnetic properties of a boron delta-layer of epitaxial silicon (charge carrier concentration being 7.10(13) cM(-2)) in weak magnetic fields ranged from 10(-3) to 2 T at temperatures between 1.7 and 50 K we carried out. The temperature dependence of conductivity was shown to be due to the combined effect of weak localization (WL) under spin-orbit interaction and hole-hole coupling (HHC) in the diffusion channel. Based on the data on temperature dependences of magnetoconductivity and Hall effect, the contributions from the WL and HHC effect were separated and their typical parameters were determined. The magnetic field dependences that are described with a high degree of accuracy by the WL expressions not involving the HHC in the diffusion channel were used to obtain absolute values and temperature dependence of phase relaxation time of the electron wave function tau(phi) proportional to T-1, indicating the dominant role of hole-hole interactions in inelastic relaxation at low temperatures. Comparison between magnetoresistances in magnetic fields perpendicular and parallel to the delta-layer made it possible to evaluate the effective thickness of the quasi-two-dimensional hole channel which appears to be equal to (8.5 +/- 0.5) . 10(-9) m throughout the whole temperature range studied.